Talk:Solar greenhouse (technical)/Archive 1

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Copy from Greenhouse effect talk page:

Contents 1 How do GH's work? 2 Re-write 3 Real green house 4 Origin of Name 5 More how stuff works 6 When the discussion is going nowhere ... 7 Use Reason 8 Horticern 9 Stop! 10 Convection 11 'ell I be - what a fine mess :-) 12 Approaches to a question 13 thermal frequencies? 14 Points of contention 15 Sue Ann Bowling webpage 16 Atmospheric Convection 17 IR Calculations and Sky Temperature 18 Temporary injunction

How do GH's work?

Are there materials which are equally transparent at visible and infrared wavelengths? If so would a greenhouse made of those materials still work?

I think it would still work, because a big effect of a greenhouse (as opposed to the atmospheric greenhouse effect) is the suppression of convection, not just radiation.

I maybe wrong. Anybody know?

See the end of [1] for an argument supporting the above.

(SEWilco 22:04, 15 Aug 2003 (UTC)) Bad link. From the comment below, apparently it is the Woods reference which is in the main article.

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I would say greenhouse built with different materials will accumulate heat at a different rate if the convection in both cases are kept the same.

I disagree with the conclusion made by the Woods' experiment in your link above. I think his experiment has a flaw that his two boxes are made of black cardboards. So as the walls of the box are heated by the sun from the outside, the heat transfer and radiated as infrared from the inside surface of the walls into the interior. Basically, the heat transfer by the cardboards overwhelmed the greenhouse effect. I couldn't believe such a flawed paper could be written by a professor!

(SEWilco 22:04, 15 Aug 2003 (UTC))

• It says the boxes are packed in cotton. I think this means the sun does not hit the sides of the boxes, so only the window is exposed to the sun.  ::* He's waiting for temp to stabilize, so he's depending upon radiation from the box to match what is captured. With the cotton insulation, heat can only leak out the plate, thus he's trying to measure the difference between radiation which can leak out of the two boxes.
• He states rock salt is transparent to the black box radiation frequency at the equilibrium temperature. A real world greenhouse has a lot of water vapor -- what frequencies does hot water vapor radiate? Is there a difference between temp of a dry and a damp greenhouse?
• He states there is a small temperature difference. Maybe that is significant but seems small in his experiment. What is the size of the boxes, and what is the temp difference for larger boxes? If radiation on one square centimeter causes small temp rise, does a thousand square centimeters also only cause that same rise?
• He doesn't state it, but I think he believes the rock salt panel has similar insulation behavior as the glass, so convection off the panels should be similar.
• Opening a box, like opening windows on a car, merely allows cooler/warmer air to circulate, and does not indicate anything about the greenhouse effect unless the total air temp is measured.
• Also if the glass "stops the longer wavelengths" then the glass is either reflecting them or is being heated by them -- the glass is probably hotter than the rock salt because of the heat being removed by the filtering glass plate above the rock salt plate, so the temp of the glass container is distorted by the hot glass panel (but this would skew upward the glass temp, so as he saw little difference the glass box would have been cooler without hot glass).

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(SEWilco 04:04, 20 Aug 2003 (UTC)) So, do greenhouses really block outgoing radiation or not? I find it hard to believe the Wood experiment is correct, or it would be a standard demonstration in every junior high school physics class.

Re-write

I saw a really clear and precise explanation of the greenhouse effect at a website. But I hesitate to rely on it without some checking from the Anome or Axelboldt or anyone else who really knows the science.

of all the sunlight that passes through the atmosphere annually, only 51 % is available at the Earth's surface to do work. This energy is used to heat the Earth's surface and lower atmosphere, melt and evaporate water, and run photosynthesis in plants. Of the other 49 %, 4 % is reflected back to space by the Earth's surface, 26 % is reflected to space by clouds and atmospheric particles, and 19 % is absorbed by atmospheric gases, particles and clouds. [2]

(William M. Connolley 22:07, 8 Sep 2003 (UTC)) Yes. But this isn't a description of the GH effect. Its a picture of how solar radiation is distributed through the atmos. But I've used it in my re-write.

I like the percentage breakdowns [But they are illustrative only: they would vary strongly in space and time. WMC]. The mention of clouds is especially interesting, because one theory is that higher temperatures will evaporate more seawater and increase cloud cover. This would increase the percentage of solar radiation reflected by clouds and decrease the percentage that hits the earth's surface. Could this be a self-regulating effect of the atmosphere? Does the greenhouse effect come with a "thermostat"?

Maybe it depends on how much warming is causd by trace gases, and how much cooling is caused by increased cloud cover. Has anyone studied that? (How about the IPCC, since they're such highly regarded experts?) --Uncle Ed 17:07, 8 Sep 2003 (UTC)

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(William M. Connolley 22:07, 8 Sep 2003 (UTC)) I have done a major re-write of the how-GH-effect works section, using the model I like, from the "bad greenhouse" page. This has now relegated the former explanatory link to a terrible example of how to get it wrong. Sorry. The text is somewhat untidy and perhaps over-pernicity in places, I look forward to its evolution.

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Real green house

The paragraph in the section titled "Real green house" is the most stupid and unscientific statement I have ever seen. The foundamental principle is how the glass let radiation (e.g. ultraviolet, visible light) in and then after the energy is converted into another form (e.g. infrared), the glass don't let it out. The basic principle was dismissed by a ridiculous claim that, when you open the window the greenhouse won't work. Hence it was concluded that the greenhouse works on the principle of convection. Such conclusion is really laughable. When you open the windows, you introduced the convection that carried the heat away. It does not prove that the greenhouse works by convection, you can only claim that the greenhouse is ruined by convection. The better set of experiments is as follow:

• eliminate the radiation and conduction from the greenhouse

built a greenhouse with insultated, oplaque walls and roofs and see how the heat get in without conduction nor radiation.

• eliminate the conduction and convection from the greenhouse

built a greenhouse with doublepane glass and no windows and see how the heat build up without conduction or convection.

• eliminate the radiation conversion that is the main principle of greenhouse effect.

built a greenhouse as the last one, but coat everything inside the greenhouse with mirror surface and then measure how the greenhouse does not work when there is no infrared to trap by the glass.

The argument about the opening window is flawed because when you open the window, you are looking at a totally different system, instead of just the greenhouse's relation with the sun, you are looking at the greenhouse plus the surround air. If you want to compare the earth to a glass greenhouse, then you cannot open the window to vent the hot air, because you can put a giant tube that poke into outter space and pump the hot air away, you can stop the global greenhouse effect just like you open the windows of the glass house. On the other hand, if you can build a large enough greenhouse where its roof is above the atmosphere, then whether you open the window on the roof or not will make no difference to the temperature inside the greenhouse. Therefore the global and glass greenhouse work the same way except that the convection effect overpowers the greenhouse effect when you have a small glass house.

Kowloonese 23:10, 5 Nov 2004 (UTC)

(William M. Connolley 11:36, 6 Nov 2004 (UTC)) Well that was jolly good rant. Now go away and read: http://www.wmconnolley.org.uk/sci/wood_rw.1909.html Now notice that the same article is referenced on the page.

I was indeed referring to the flawed Wood's experiment. He wrote a paper, you don't have to agree, do you? Kowloonese 08:47, 8 Nov 2004 (UTC)

(William M. Connolley 09:28, 8 Nov 2004 (UTC)) He did the experiments. He built a non-radiative greenhouse. It worked just as well as a radiative one (as do modern plastic polytunnels which are mostly transparent to IR).

The argument about the opening window is flawed because when you open the window, you are looking at a totally different system, instead of just the greenhouse's relation with the sun, you are looking at the greenhouse plus the surround air. That's right. It is a different system. Exactly as a fanciful "pipe out to space" would make a totally different system: earth plus surrounding space insteads of just earth. In other words, the analogy in the article is entirely appropriate. Tannin 09:46, 8 Nov 2004 (UTC)

Scientific works are subjected to peer reviews. The Wood's experiment reads like baloney to me, though I am not his peer. What is the general acceptance of his conclusion in the scientific community? Anyone who has studied history of science knows that many convincing scientific theories were later proven wrong. This one is not even convincing. Why is his view stated like the gospel in this encyclopedia? It is definitely not NPOV. Kowloonese 21:34, 8 Nov 2004 (UTC)

(William M. Connolley 22:17, 8 Nov 2004 (UTC)) A peer reviewed paper definitely trumps your personal biases. What part of his experiment do you disagree with, and which of his results do you dispute. And please don't forget about the IR properties of plastic greenhouses.

I have a ridiculous argument that this analogous to the open window argument by Woods. Here it goes, prepare to laugh. I can prove that penicillin is not a cure for bacterial infection because if I cut open the patient's artery, the patient dies. The open window green house is as silly as this. It just does not make sense at all. Kowloonese 21:49, 8 Nov 2004 (UTC)

(William M. Connolley 22:17, 8 Nov 2004 (UTC)) Your argument is indeed ridiculous, but also irrelevant.

Origin of Name

How did the tern "Greenhouse Effect" originate?

A greenhouse, [3], is a clear glass structure in which plants are grown (thus, making it appear green from all the plants). The environment inside of such a structure is warmed because of the "greenhouse effect", which is that light goes through the glass, strikes the plants/ground warming them, and then the thermal radiation which would radiate back out is partially reflected by the glass. Therefore there is a net warming effect. (example picture: [4]) — Cortonin | Talk 03:00, 22 Jan 2005 (UTC)

I never stopped to consider describing the origin of the term on here. Do you think the article would benefit from a short summary of its etymology? — Cortonin | Talk 03:00, 22 Jan 2005 (UTC)

(William M. Connolley 12:05, 22 Jan 2005 (UTC)) Sigh. Why don't you read the page, the section "Real greenhouses"? Greenhouses do *not* operate by the GHE. Who first started this incorrect analogy would be interesting, though. And thermal radiation isn't reflected by glass, of course.

Yeah, it seems that section was based on a very short 1909 paper (which compares a medium which lets more NIR wavelengths in and more thermal wavelengths out, with glass, and then tweaks the setup until they come out balanced). Regardless, we have better experimental methods now with more modern materials, and an entire industry that works on just this. I fixed that section, and included three references: A textbook which discusses the mechanism, a website targetted toward laymen, and a research paper on modern greenhouse design where radiative transmittance is selectively controlled to regulate growing conditions. — Cortonin | Talk 19:40, 22 Jan 2005 (UTC)

(William M. Connolley 20:03, 22 Jan 2005 (UTC)) Read the Wood paper. It shows that a structure transparent to IR heats up just like one opaque to IR. To quote: This shows us that the loss of temperature of the ground by radiation is very small in comparison to the loss by convection, in other words that we gain very little from the circumstance that the radiation is trapped.. Those results remain valid. The IR properties of the covering have an effect, but a minor one. I am told (though I've never verified it) that many plastics used are in fact transparent in the IR region anyway.

You should reread it, in the first run the rocksalt enclosure got HOTTER. Then he places them both under glass and they both reduce until they are equal. What happens if he places them under two pieces of glass? It was clearly not a very thorough experiment, as his concluding paragraph states, yet far more thorough research has been done in the intervening 100 years which shows his conclusion incorrect. We have an industry designed around making enclosures that regulate greenhouse temperatures by selecting radiative properties. The plastics used are not transparent in the thermal IR region, usually only in the NIR region. They are selectively designed (based on climate desired) to keep thermal IR inside, as clearly described on the third reference I added. Please do NOT revert before READING the sources I added. — Cortonin | Talk 20:12, 22 Jan 2005 (UTC)

(William M. Connolley 09:30, 24 Jan 2005 (UTC)) Yes indeed, the Rocksalt encloser did get hotter. Which demonstrates quite conclusively that transparency to IR doesn't prevent warming. You added: However, convection can only act to bring the temperatures inside and outside of the greenhouse into balance.. This makes no sense: temperatures inside and outside *aren't* in balance: thats the point: its warmer inside.

(William M. Connolley 12:30, 24 Jan 2005 (UTC)) I've added some extra links. In case you have trouble finding the texts, let me quote:

temperatures in a greenohuse are not to be attributed to the absorption of long-wave radiation by the glass (Fleagle)

It has nothing to do with greenhouses, which trap warm air at the surface (Henderson-Sellers)

this phraeseology is somewhat inaapropriate, since CO2 does *not* warm the planet in a manner analogous to the way in which a greenhouse keeps its interior warm (that by Sherwood Idso, a noted skeptic, in case you're thinking this is some vast conspiracy)

The term greenhouse is somewhat of a misnomer... actual greenohuses work primarily in preventing the turbulent removal of heat... the emissivity of the glass panes to infrared radiation is generally insignificant (Cotton and Pielke, Human impacts on weather and climate (a generally mildly skeptic book)

You know why "skeptics" are the ones saying the point you're arguing in favor of here? It's precisely because by that same argument, more of the Earth's temperature is determined by convection than by the greenhouse effect, because convection is a more significant contributer than the greenhouse effect. And that's definitely true, as I have had comment about in that last paragraph. Similarly, more of a real greenhouse's temperature DIFFERENCE from the outside comes from the ABSENCE of convection, than from IR, but there IS still a significant contribution from IR opaqueness. Greenhouses do not heat up by convection supression. Measure the temperature of a glass room at night with no light, and will not just sit there and heat up because there is no convection, that would violate the laws of thermodynamics. Greenhouses heat up from the solar light which enters, and they gain additional heating over a completely transparent media from the thermal IR which glass is highly opaque to. Modern greenhouses are even made of materials specially engineered to select the amount of heating from thermal IR opacity (which clearly is only done because the contribution from thermal IR opacity IS significant). Arguing that the two are different phenomena because gardening greenhouses would be cooled off partly by convection if it were permitted is just toying with semantics, because the same thing applies to the global greenhouse effect. While you're at it, you could argue that gardening greenhouses function by an absence of liquid nitrogen being pumped into them, because clearly the right amount of liquid nitrogen would cool them off to the outside temperature. The argument would be the same. — Cortonin | Talk 19:12, 24 Jan 2005 (UTC)

(William M. Connolley 20:53, 24 Jan 2005 (UTC)) This is stupid. I've provided refs from a variety of atmospheric science sources showing that the term is a misnomer. Even if you happen to disagree with the science (though I don't undrestand why you do) you need to accept the wiki policy of (a) reporting the maainstream view and (b) no original research. Every atmospheric science text that thinks about the name conclude its a misnomer. I've never seen even one that says "people say its a misnomer, but it isn't". If you have a radiative physics background, thats nice, but totally irrelevant: wiki isn't here to represent your views (or mine) but what the science has written down. And whats written, time and again, is that the name is a misnomer.

Did you even read the sources I posted? Yes or no? If you did perhaps you would have seen a few sources that disagree with you. Allow me to quote from NPOV#Avoiding_constant_disputes:

How can we avoid constant and endless warfare over neutrality issues?

The best way to avoid warfare over bias is to remember that we are all reasonably intelligent, articulate people here, or we wouldn't be working on this and caring so much about it. We have to make it our goal to understand each others' perspectives and to work hard to make sure that those other perspectives are fairly represented. When any dispute arises as to what the article should say, or what is true, we must not adopt an adversarial stance; we must do our best to step back and ask ourselves, "How can this dispute be fairly characterized?" This has to be asked repeatedly as each new controversial point is stated. It is not our job to edit Wikipedia so that it reflects our own idiosyncratic views and then defend those edits against all-comers; it is our job to work together, mainly adding new content, but also, when necessary, coming to a compromise about how a controversy should be described, so that it is fair to all sides.

This is official Wikipedia policy, so it would be nice if you considered following it here. The statements I have added to the "Real greenhouses" section, I will stress, are documented, so your comments about "original research" are not related. The sources I have documented are ALSO mainstream, so please leave them, along with their description, as a source of further information.

In an attempt at compromise, I have placed both interpretations side-by-side. This should be acceptable, so PLEASE DO NOT REVERT IT. Have faith in the reader, and let the reader decide. — Cortonin | Talk 07:01, 25 Jan 2005 (UTC)

(William M. Connolley 09:41, 25 Jan 2005 (UTC)) For the moment, that will do as a compromise. I don't think it can last for ever, but I'm happy to give other people the chance to read both versions and comment.

Thank you. — Cortonin | Talk 18:47, 25 Jan 2005 (UTC)

To help ease your conscience, contemplate this explanation: Convection will only act to equilibrate two temperatures, so if there were no radiative imbalance contribution, then everytime the outside air was cooler than the ground, the greenhouse would be warmer than the outside air and ground, and everytime the outside air was warmer than the ground, the greenhouse would be cooler than the outside air and ground. Yet this does not seem to happen. This is such a "specific" result that it's very unlikely to find it documented, and it's too specific to be useful to the article, but it's very easy to derive the result for yourself (it would make a nice undergrad thermo problem). If radiative imbalance were not a contributer, and there was no atmosphere, then the ground and greenhouse would reach the same temperature by conduction. Then when you apply the atmosphere to the system, if the atmosphere is warmer than this temperature, the convection theory proposal is that it warms the ground but not the greenhouse, thus making the ground and atmosphere warmer than the greenhouse, or if the atmosphere is cooler than that temperature, it cools the ground but not the greenhouse, thus making the atmosphere and ground cooler than the greenhouse. Now this is clearly not how actual greenhouse temperatures behave, but that's because in actual greenhouses, there is a radiative imbalance which raises the temperature above that point. Spend some time thinking about the system I just tried to describe, and then hopefully you'll see. — Cortonin | Talk 18:47, 25 Jan 2005 (UTC)

Mr Connolley worships the flawed Wood's experiment and his flawed conclusion as gospel. I don't think you would be able to change his mind. See a few sections above. There were some debate that didn't go anywhere. Doing it all over again will not change a thing. Kowloonese 01:19, Jan 26, 2005 (UTC)

WMC, if you were to read the above more carefully, you might understand why the argument you're putting forth is physically invalid. The fridge analogy is this: The mechanism by which a fridge operates is by application of a heat pump. What you're implying is that the fridge operates primarily by suppression of convection, because if you open the door to the fridge it will be close to the temperature that it is outside. Obviously this is backwards logic. If you unplug the fridge, it STILL has suppression of convection, yet obviously all of your food will spoil. So clearly suppression of convection is not the mechanism by which the fridge operates. The primary mechanism is the mechanism which causes the temperature difference, and this is the heat pump (or in the case of the greenhouse, the radiative imbalance). Certainly the fridge WILL bring its temperature close to equilibrium if you leave the door open, but this is because the presence of convection undoes the mechanism by which the fridge operates. Similarly, if you place a toaster oven on high inside of a closed fridge (with a cord running inside), you will also find the inside of the fridge staying close to the outside temperature. Does this mean that a fridge operates by an absence of toaster ovens? Clearly not. — Cortonin | Talk 15:40, 21 Feb 2005 (UTC) If you want to do a proper experiment, take a greenhouse and bury it. Then there will be no radiative imbalance at all. You will find the temperature inside the greenhouse will be the same as the temperature of the ground, not hotter, even though there will be suppression of convection. Likewise, a greenhouse sitting on the surface fully exposed would reach equilibrium with the temperature between that of the ground and the atmosphere if there were no radiative imbalance. Instead, in reality there IS radiative imbalance, and a greenhouse can get hotter than either the ground or the atmosphere. And in fact, radiative imbalance is the only physically valid way that a greenhouse's temperature can exceed that of both the ground and atmosphere. This is elementary thermodynamics. The inside of a car cannot be hotter than the temperature of the surfaces it is contacting without work being done, and that work is done by a radiative imbalance. Anything else would violate conservation of energy, and yield a spectacular perpetual motion machine. — Cortonin | Talk 15:40, 21 Feb 2005 (UTC)

(William M. Connolley 21:39, 21 Feb 2005 (UTC)) I don't think you've understood this at all. The fridge analogy is irrelevant. The physics is: heat comes in (solar radiation). Heat is retained inside the GH, so it warms up, more than does the outside world. The question is, what is retaining the heat? There are two posibilities: that it is primarily the radiative properties of the glass (or plastic, or whatever); or primarily the physical-barrier properties of the glass. We know its not the radiative-barrier properties of the glass because (a) we can replace the glass by something transparent to IR; and it still heats up (b) we can open a small window (that does not strongly affect the radiative properties, but does affect the physical-barrier properties) and it cools down. So the important effect is the physical barrier that the glass presents to the movement of tthe air heated by contact with the surface.

If you replace the glass by something transparent to UV through IR, then the inside of the greenhouse will only be hotter if the temperature of the outside ground is warmer than the temperature of the outside air, because this is the only case in which the convection would cool the heating of the outside ground. However, this is only the case part of the time, as the rest of the time the temperature of the outside ground is actually cooler than the outside air, and in that case the greenhouse with the fully transparent material would be cooler than the outside air. Obviously real greenhouses do not do this, because there is in reality a radiative imbalance. It does not get any clearer than that. — Cortonin | Talk 02:39, 23 Feb 2005 (UTC)

That Wood experiment is seriously flawed, incomplete, and outdated. You should not rest so heavily on it. — Cortonin | Talk 02:39, 23 Feb 2005 (UTC)

(William M. Connolley 10:22, 23 Feb 2005 (UTC)) You should have a bit more respect for published research, and actually read it. Woods clearly states: When exposed to sunlight the temperature rose gradually to 65 oC., the enclosure covered with the salt plate keeping a little ahead of the other, owing to the fact that it transmitted the longer waves from the sun, which were stopped by the glass. In order to eliminate this action the sunlight was first passed through a glass plate. The inside is slightly warmer with rocksalt because it passes IR from the sun. This was then controlled for.

I think you idealize scientific literature a bit if you expect me to take a six paragraph paper from 1909 seriously which has conclusions which violate basic principles of thermodynamics just because it's "published". I read the Wood paper on a link you posted. First, the Wood paper itself ends with, "I do not pretent to have gone very deeply into the matter", which clearly he didn't. The "control" mechanism you describe there is a completely faulty control mechanism. Surely you don't think one piece of glass and one piece of rock salt is a control for either one or two pieces of glass (the paper is ambiguous as to which amount was used for the second arrangement, despite how critical this is, and is also ambiguous about the spacing between these plates. Are they on top of each other, or is there ventilation between them?). An incomplete experiment with a defective control mechanism from 100 years ago is hardly grounds for throwing out the conclusions of an entire greenhouse manufacturing industry worth of research. You should have a bit more respect for the standards of quality in science. — Cortonin | Talk 13:48, 23 Feb 2005 (UTC)

(William M. Connolley 10:22, 23 Feb 2005 (UTC)) For reasons that are unclear to me, you are attempting to insert text that directly contradicts perfectly clear statements in a large number of meteorological textbooks and the published literature with what amounts to personal research. You can't do that.

Basic thermodynamics is hardly "personal research". I make no claim to have invented the field. If you note the two sections in dispute carefully, you'll see that the section you are supporting has three reference links, one called "Bad meteorology" which makes an allusion to the Wood paper, one on your personal website where you present the Wood paper and selectively agree with some of his conclusions while disagreeing with his other conclusions, and another reference which simply references the Wood paper. Then you list three textbooks from the early 80's which I obviously don't own, and I'm not about to go purchase just to verify your claim that they say something about the mechanism of real greenhouses. Perhaps you could quote the precise and full text in which each of those three textbooks makes a claim about the mechanism of a real greenhouse. — Cortonin | Talk 13:48, 23 Feb 2005 (UTC)

In comparison, the section you keep erasing is referenced with five CLEARLY ACCESSIBLE and independent sources from a variety of locations. If you want to talk about something you shouldn't do, deleting something that clearly documented by replacing their conclusions with your own conclusions is something you shouldn't do, and I would kindly request that you stop doing so. — Cortonin | Talk 13:48, 23 Feb 2005 (UTC)

You seem to have either not read or completely not understood the descriptions I gave above which make it clear why convection suppression is not the "mechanism", and why opening a window in a greenhouse tells you nothing about the mechanism of its operation. If there is something specific which is unclear about those descriptions, please state what it is and I will try to make it more clear. — Cortonin | Talk 13:48, 23 Feb 2005 (UTC)

(William M. Connolley 22:35, 25 Feb 2005 (UTC)) I've now added quotes from two meteorological/climatological sources which say, with no qualification, that it is a misnomer. This is a meteorological subject. You should accept their expertise. I've also put a description of the basic physics on this talk page. If any of that is unclear, do let me know, and I will try to clarify it.

It's not a meteorological issue, it's a physics issue.

(William M. Connolley 21:15, 26 Feb 2005 (UTC)) Only in the rather meaningless sense that all the world is physics.

The function of a greenhouse is the domain of thermodynamics, not meteorology. The only arguments you have presented here is the Wood paper, which is a bad and incomplete experiment easily countered by the more recent and thorough examples I referenced,

(William M. Connolley 21:15, 26 Feb 2005 (UTC)) This is just wrong. The woods expt is good, and still valid. You have referenced nothing 1/10 as relevant. You're also conveniently forgetting the two direct quotes from met books.

And you're ignoring the physics. See the description below. You pretend to be all pro-science and act like you're fighting the good fight against anti-science, but when I present you with a clear description of the science you fall back to an obscure reference and a non-detailed quote from a textbook. Are you really interested in understanding the science, or are you just trying to be right? Conservation of energy is not an optional rule here. Work must be done to create a temperature imbalance, and in an insulated system that work is done by a radiative imbalance. — Cortonin | Talk 08:10, 27 Feb 2005 (UTC)

and the argument you seem to have made up that opening a window in a greenhouse tells you something about how it functions. The window argument is wrong. Adding an additional method of equalizing temperatures does not show the mechanism by which unequal temperatures were reached. The natural path of all things is to equalize temperatures (the second law of thermodynamics), and the only way to create unequal temperatures is to do work. The thing which does the work is the mechanism by which the item operates, which in this case is a radiative imbalance. — Cortonin | Talk 00:28, 26 Feb 2005 (UTC)

I believe WMC has confused which is the chicken and which is the egg. The term Greenhouse effect was a physical phenomenon way before the meteorologists borrowed the term to describe a global phenomenon in similar principle. Now the original term is redefined because the meterologists said so. The green house and the Earth would behave the same if the glass roof of the greenhouse can be theoretically raised above the atmosphere. But since no one can build such a big green house, a regular greenhouse will be overpowered by convection which is not observed in the global greenhouse. Kowloonese 06:05, Feb 26, 2005 (UTC)

More how stuff works

Vsmith, I see what you're trying to say in that latest addition to the thermal IR section, and there is value in trying to describe the mechanisms in more detail like that. But you have two aspects slightly incorrect in that description. First, you place an emphasis on the directional focus of the radiation, but it turns out when you do the math that the only things that matter for determining the equilibrium temperature is the radiation going through the gateway (in this case, through the glass). Second, you wrote "The amount of infrared radiation reaching the greenhouse covering is considerably less than the incoming radiation". This is incorrect, because with sufficiently insulating glass, the heat loss due to direct thermal contact through the glass and ground will be small, and the equilibrium temperature will be defined by the point where the radiative flux out nearly matches the radiative flux in. — Cortonin | Talk 10:08, 26 Feb 2005 (UTC)

Added heading above - section way too long - got lost navigating :-) Anyway let's see, about the first: ...emphasis on the directional focus of the radiation, it seems to me a homely example might work here, the sun shines through my south window in the winter (not so much today as it's cloudy) and strikes the floor. I put my bare feet on that illuminated spot and viola it is warm, I step a few inches to the side and it's not warm. Line up that warm spot, the window, and the sun - there is definitely directionality there - hmm. The non-directional warming or radiative heat transfer within the atmosphere is an important factor in warming the surface and objects on the surface. But that is mostly IR and you stress that IR don't get out through the glazing - well then logic implies that it can't get in that way either. So it seems the main energy source would be the directional short wavelength radiation from the sun - I think the term solar greenhouse implies that connection.

Yeah, that section was getting hard to scroll through.  :) As for the directionality, it is true that the solar radiation is directional, certainly. The blackbody radiation generated inside the greenhouse goes in every direction, and the fraction that is pointed out through the glass is actually a factor in the equations below, and shows up as a geometric component in the constant C (which is constant for each particular greenhouse), because the component responsible for balancing is only the portion which goes out through the glass, so this is the fraction that aims toward the glass times the fraction that goes through. But the geometric component is not the reason for the warming, since if you remove the glass it would be the same as the ambient temperature. — Cortonin | Talk 17:41, 27 Feb 2005 (UTC)

the second: I agree that given sufficient time, without input from the directional sunlight, equilibrium will be established via all those physics equations below :-) (and, yes I have read and at least think I understand what you are saying). However, the blocking of the convective part of that equilibrium seeking process by the glazing is the major factor in keeping the greenhouse warm for the short term until the sun shines again. The greenhouse doesn't reach equilibrium with the outside air because the convective path is blocked - and the sun comes back up hopefully long before the radiative and conductive processes (which keep on working) can equalize the temperature.

The IR absorbance is also a factor in maintaining this. Try it yourself on a cool night. Sit by a window with the curtains closed, and then with the curtains open. The window will block some thermal IR, but the curtains will block almost all, and this will make a noticeable difference in the temperature. — Cortonin | Talk 17:41, 27 Feb 2005 (UTC)

I'm well aware of this, the south end of my house, both stories, is glazed. The big drapes were quite expensive. I see agreement that glass is not opaque to IR or that conduction works quite easily through glass. I know that modern insulated glazing materials cut way down on this. However, you seem to be partly agreeing that the major factor retaining heat overnight within a typical old fashioned greenhouse is the lack of convection with outside air. Noting, of course that thermal equilibrium is not reached overnight by a good amount, assuming enough mass present for heat storage - otherwise greenhouses wouldn't be worth much. -Vsmith 00:46, 1 Mar 2005 (UTC)

Certainly if you had outside air flowing into the greenhouse, the temperature will match the outside temperature quickly. This is no different from leaving the refrigerator door open, which will cause the temperature inside the refrigerator to match the temperature in the room. And I think I typed a section which clearly states that within the thermal IR section. What you need to be careful to avoid, is you need to avoid saying, "opening the refrigerator makes it warm, so the refrigerator gets cold because the door is closed." Obviously we all know the refrigerator does not get cold simply by having a closed door. It just, for some reason, seems to be harder to convince people of this when it comes to the greenhouse, because they can't see where the electrical cord is running. If you want another analogy, does an oven get hot because it is a sealed container, or because there is a heating coil in it? If you allow convection by opening the oven door, it doesn't get very hot. So then what is it that makes the oven get hot? It's still the heating coil. — Cortonin | Talk 05:14, 1 Mar 2005 (UTC)

And I should probably add that glass is not completely opaque to IR, it's only partially absorbant. This is part of why the thermal glazings are helpful. What you seem to be searching for, is some sort of equation which equates the rate of thermal IR loss through conventional glass to the rate of cooling through an open window of a certain size. The size of the open window which would equate the rate of energy loss as thermal IR at night would vary for every single greenhouse and would vary as a function of the internal temperature of the greenhouse and the outside temperature. However, I'm not sure why you're looking for this relationship, because it doesn't tell you anything about how the greenhouse operates. — Cortonin | Talk 05:14, 1 Mar 2005 (UTC)

I don't believe I said anything about open windows or any refrigerator analogy. So I have no clue what the above paragraphs have to do with my discussion. Vsmith 04:29, 2 Mar 2005 (UTC)

I'm simply trying to find as many ways as I can to explain it to you, since you still seem to be not getting it. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

And finally, here's one for you to consider. If you park a car in a greenhouse, will the inside of the car get hotter than the greenhouse? Thermodynamics tells us yes. Do you understand why? Clearly it's already convection isolated from the outside world, yet it still gets hotter than the surrounding greenhouse. This is because the greenhouse reaches its greenhouse temperature, and then the inner parked car still has a radiative imbalance, forcing it to a higher temperature relative to its environment (the greenhouse). This so called "greenhouse-in-a-greenhouse" effect is used in gardening to heat water pipes within a greenhouse, or to place transparent plastic sheets over plants within a greenhouse to keep them even warmer. — Cortonin | Talk 05:14, 1 Mar 2005 (UTC)

and...? Convective isolation is the key, seems like you've just proven it. :-) Vsmith 04:29, 2 Mar 2005 (UTC)

?? I just proved that convective isolation cannot possibly be the key. If convective isolation were the key, then a parked car inside a greenhouse would not get hotter than the greenhouse, because it's not "more isolated from the oustide world". The only reason it gets hotter is because it has a further radiative imbalance pushing it hotter than its ambient environment, the greenhouse. This is not powered by convection or by lack of convection. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

Thermal equilibrium and the greenhouse.

1. At thermal equilibrium the avg. thermal energy (temperature) within a container (the greenhouse) is equal to the avg. thermal energy outside.

2. At thermal equilibrium the thermal energy flow in is equal to the thermal energy flow out.

Which are you talking about?

The second one, of course. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

In a properly functioning greenhouse and in the atmosphere #1 is never achieved.
In a properly functioning greenhouse and in the atmosphere #2 exists briefly in transition twice daily. After the sun comes up and the directed radiation hits the glazing the net energy flow switches quickly from IR and conduction out > than IR and conduction in to short wavelength radiation in becomming much greater than IR & conduction out. After the sun sets the situation reverses. Thus two brief periods of energy flow in = energy flow out. But due to the brevity of the event I wouldn't call that equilibrium at all. Which of the two is your concept? No equations needed just tell me which you are referring to. Vsmith 04:29, 2 Mar 2005 (UTC)

The greenhouse can be considered in approximate thermodynamic equilibrium for most of the day, except early in the morning when the sun comes up and the temperature is rising significantly, and early at night when the temperature is dropping significantly. When the temperature is not changing significantly, as for most of the day, then it can be considered in equilibrium. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

In regards to your recently added spectroscopy reference. 90%+ irrelevant to this article. And the one relevant paragraph contains a serious misconception which renders it suspect or invalid. "The fact that water vapor, carbon dioxide, and other gases reflect infrared light is important in determining how much heat from the Earth is lost through radiation into space. This phenomenon, often called the greenhouse effect"[5] is a serious mis-statement of the concept. Why would you even include the reference? Vsmith 04:29, 2 Mar 2005 (UTC)

Uh, what do you mean this is a serious misstatement? That's precisely what the greenhouse effect IS. That page is from the analytical spectroscopy research group at UKY. The greenhouse effect is the convergence of thermodynamics (which describes systems involving temperature) and spectroscopy (which describes systems involving the interaction of light and matter), and these people do spectroscopy research (making them experts on this). I assure you that paragraph is correct. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

I can see clearly now, all those little molecular mirrors up in the sky reflecting all that IR light back to us. Must keep a herd of little elves busy polishing each molecule. :-) Vsmith 13:00, 2 Mar 2005 (UTC)

Minus the elves, that's kind of how it works. Each molecule will absorb an IR photon, which gives an electron a certain amount of energy. But that energy has to go somewhere, and it goes somewhere as an IR photon emitted in a random direction. Let's, for a simple description, consider the atmosphere as having a "bottom layer". So that bottom layer can emit the photon down, in which case it is essentially reflected back to the ground, or it can emit the photon up. But each photon emitted up has a chance of striking an atom from another layer of the atmosphere, which will reemit it in a random direction, giving it another chance to go down into the atmosphere. The average end result is that all thermal IR either escapes to space, or is reflected back down to the surface. (There is a small complication induced by the Stoke's shift of the reemitted photons, which will give a small amount of heat energy to the atmosphere, but this too will have the end result of thermal IR being emitted in a random direction, making the end result essentially equivalent to the simple form of radiation either escaping or being reflected back down.) — Cortonin | Talk 23:03, 2 Mar 2005 (UTC)

For a more intuitive level of thinking about it, you can picture what happens when you turn on the high beams of a car in thick fog, and it scatters bright light back at you. — Cortonin | Talk 23:03, 2 Mar 2005 (UTC)

This is what my elves were saying: Sometimes diagrams are drawn which show the radiation from the Earth's surface rising into the sky and being reflected off of the atmosphere (or clouds, or greenhouse gases). This too is nonsense. The radiation was not reflected, it was absorbed and different radiation was subsequently emitted. [6] Your ref. may be very good w/ spectroscopy, but the relevant paragraph is perpetuating a myth. Vsmith 01:35, 3 Mar 2005 (UTC)

Argh, I just typed a long reply to this and then I seem to have closed the browser window. That was a spectacular maneuver. In shorter form this time, your elf has some physics incorrect on that page. He says, "But, upon being absorbed, the radiation has ceased to exist by having been transformed into the kinetic and potential energy of the molecules." This is not quite correct. The only reason greenhouse gases absorb radiation is because they have an energy transition right at the energy level of thermal IR photons, for which upon absorbing such a photon, an electron moves into an excited state. The most common decay pathway for an excited electron like that is to decay into the ground state emitting a photon of approximately the same wavelength. — Cortonin | Talk 09:25, 3 Mar 2005 (UTC)

In addition, when the term "reradiate" is used, it is not used to refer to photons somehow being saved and then rereleased, but is instead simply used to refer to the energy being radiated again. — Cortonin | Talk 09:25, 3 Mar 2005 (UTC)

I'm perfectly willing to explain any of this to you that still doesn't make sense to you, but please don't engage in an edit war over this until AFTER understanding the description of the system. The goal of an encyclopedia is to inform people, not to fight over informing them. — Cortonin | Talk 08:16, 2 Mar 2005 (UTC)

Ah yes, I'm just a dumb old geologist and don't know much. Just playing around a bit :-) But, I do seem to have accomplished a bit here. If you, Cortonin, will back off a bit and take a close look at what's been going on here. Your reaction here with me is exactly what you keep accusing WMC of doing. Can you see that? Now the difference, I know that WMC is an expert in his field and can respect that. However, who are you? You obviously know a bit of science, at least some jargon, - but beyond that I haven't a clue. And all them little mirrors in the sky ... Vsmith 13:00, 2 Mar 2005 (UTC)

With the slight exception of defending the spectroscopy researchers from too much ridicule, I'm not trying to make any arguments from authority here. I usually don't find them particularly useful when explanations of the phenomena are possible instead. If you knew my background you might take my description of this as true on the basis of that, but this isn't exactly the wiki way. I have gone to great lengths to try to explain the phenomenon, because I believe that if one of the editors is confused about something, then a large number of readers will be too, and so there is value in working through ways to more clearly explain this. I think we've accomplished something with all this talking, I'm simply hoping that I can explain it clearly enough to you that you can help explain the correct description of whatever it was that was confusing you at first, so that other readers aren't confused. — Cortonin | Talk 23:03, 2 Mar 2005 (UTC)

The primary difference between my approach and WMC's approach, is that my goal is not to persuade you to let me keep my version. My goal is to explain it to you (or anyone following the talk), so that you help clarify the correct description. — Cortonin | Talk 23:03, 2 Mar 2005 (UTC)

It also strikes me that you may still be confused about the directionality issue, so let me try again to explain that. From the math which describes the system, as seen below, you can of course see that directionality of radiation is not an issue. But you can also see this on an intuitive level. Consider the interaction between a tree and the ground, both inside a greenhouse. Some of the thermal IR that the ground radiates strikes the tree. And similarly, some of the thermal IR that the tree radiates strikes the ground. This can be completely neglected, however, because in equilibrium when the tree and ground are the same temperature, the radiation between the two completely balances out. And the radiation from the ground that would have gone out through the glass if not for the tree is replaced by radiation going out from the other side of the tree, so nothing is really lost here. The only thing that needs to be considered is the radiation into the system and the radiation out of the system. This is fairly standard when describing thermodynamic systems. — Cortonin | Talk 08:32, 2 Mar 2005 (UTC)

---

Maybe this whole section of the article belongs in the greenhouse article rather than here. Of course that would embroil that article in the controversy - but would be more relevant there.

-Vsmith 15:14, 27 Feb 2005 (UTC)

Well, the greenhouse page is more about the gardening applications. It would probably make more sense for the greenhouse page to link here, to the greenhouse effect (which it does). I think it's best here, first because that IS what the greenhouse effect is, and secondly because there seem to be questions about this that readers are seeking to resolve by coming to this page. — Cortonin | Talk 17:41, 27 Feb 2005 (UTC)

It seems to me it's nonetheless having a seriously distorting effect on both the structure of the page, and the resultant discussion. For all intents and purposes the two are separate in normal discourse, and the climatological sense is now the primary one. If greenhouse isn't the appropriate place for it, a separate page is always an option: greenhouse physics or greenhouse thermodynamics, or whatever. Add links all 'round. Or at least, restructure the page so that the 'real greenhouses' doesn't sound like the digression it does now, but make the two more clearly separate. At present we're getting needlessly bogged down here, essentially, on how analogous the analogy really is. Alai 07:18, 1 Mar 2005 (UTC)

Well, the climatology sense is the more common one, but the other use of the term greenhouse effect is still used quite a bit, both in gardening, and colloquially when discussing things like cars. It would be better if that section could be cast more as simply a description of how greenhouses operate when glass is involved instead of gases, rather than as a debate between two theories. I think the "bog" would be reduced if the section "convection theory" were simply removed, along with the header "thermal infrared theory", and that section were simply made the contents of "Real greenhouses", since it already includes a correct description of the role of convection. The only reason I have not fixed this is to placate WMC who will simply turn it into another edit war. If that change were made, then perhaps the description of the solar cookers and the greenhouse glazings could be merged into one slightly smaller paragraph so that it would seem like less of a digression in that portion. But I think it's important to keep a good description there of how glass greenhouses work, since apparently there is still significant confusion on this subject, and thus a description would benefit the reader. — Cortonin | Talk 07:49, 1 Mar 2005 (UTC)

For more detail, let's say F_in is the radiative energy flux in, F_out is the radiative energy flux out, F_glass is the direct heat transmission through the glass, and F_ground is the direct heat transmission through the ground. In this case, equilibrium is reached at the point where: F_in = F_out + F_glass + F_ground. (The WMC confusion comes because he's adding an F_openwindow term to the right side, completely changing the system.) F_in is a constant determined by the sun. F_out is a product of P, the fraction of thermal radiation which passes through the glass, and F_bb, the energy flux out created by the blackbody radiation in the greenhouse. F_out = P * F_bb. F_bb scales with the fourth power of the temperature, so we'll use F_bb = C * (T_g)^4, where C is a constant, and T_g is the greenhouse temperature. F_glass is determined by Newton's law of cooling, which we'll shorten to F_glass = k_glass * (T_g - T_a), where k_glass is a constant representing the rate of thermal conduction through the glass and T_a is the ambient temperature. Similarly, F_ground = k_ground * (T_g - T_a). Therefore, the equilibrium equation becomes: F_in = P*C*(T_g)^4 + (k_glass + k_ground) * (T_g - T_a). Now, k_glass and k_ground are reasonably small numbers in the insulated case, which leaves the greenhouse free to warm up to a noticeable temperature difference. In the starting condition when you "turn the sun on", T_g = T_a. There is then a radiative imbalance caused by F_in not being equal to P*C*(T_a)^4 (where in that case I use the ambient temperature, T_a). And in fact, you can see that as P gets smaller, which represents higher thermal radiation absorbance by the greenhouse glass, the P*C*(T_a)^4 is even smaller than F_in. This means that for the equilibrium equation to balance out as thermal IR absorbancy increases, T_g must grow larger, and it does. This is the mechanism by which a greenhouse actually operates. — Cortonin | Talk 10:08, 26 Feb 2005 (UTC)

(Hopefully there are no typos in the above.) Now, I'm assuming most people think the above is far too complicated to place verbatim in an article on the greenhouse effect, which is why I'm typing it here instead. Hopefully those of you who can follow the math here will understand the mechanism sufficiently from that description to work on the description in the article. — Cortonin | Talk 10:08, 26 Feb 2005 (UTC)

(And no, that is not "original research". It's a simple calculation using standard thermodynamic concepts, so please don't call it "research".) — Cortonin | Talk 10:08, 26 Feb 2005 (UTC)

When the discussion is going nowhere ...

I found a good article [7]. It may be worth reading before this page is getting way too long. Kowloonese 21:01, Mar 3, 2005 (UTC)

An interesting read.  :) I was going to suggest there should be a wiki page, but there already is. — Cortonin | Talk 05:20, 4 Mar 2005 (UTC)

Use Reason

WMC, describe the greenhouse-in-a-greenhouse effect (where a greenhouse inside of another greenhouse reaches an even hotter temperature) in terms of suppression of convection. If you are careful you will find that you cannot, because convection suppression cannot serve as a mechanism for this. You will also find, if you look, that the greenhouse-in-a-greenhouse is a well known and commonplace effect. — Cortonin | Talk 10:51, 18 Mar 2005 (UTC)

(William M. Connolley 20:27, 18 Mar 2005 (UTC)) Well feel free to reference it here. But putting a GH in a GH would appear to be a different situation to the one we're talking about.

I will help you. Think the following two scenarios through in your head. With only convection suppression, both scenarios are identical. There is no difference between B and A in temperature in either scenario, regardless of what portion of A's volume B encompasses, because there is no difference between part of region B and a corresponding size portion of A. They both receive the same incident light, and they are both isolated from environmental convection. — Cortonin | Talk 10:51, 18 Mar 2005 (UTC)

1.

A

B

2.

A B

Alternatively, thermal IR absorption yields the effect of region B being hotter than region A in scenario 2, which matches observation. There is no room for ambiguity in the physics here. — Cortonin | Talk 10:51, 18 Mar 2005 (UTC)

The real reason a greenhouse remains warmer overnight is that the main fluid heat equalizing process, convection cannot take the excess heat away. Plus if the greenhouse is designed properly heat storage mass is included to prolong the warm temperature regardless of whether the glazing is transparant to IR or not. Obviously, the use of insulated IR reflecting or absorbing glazing material will reduce heat transfer by both radiation and conduction and make a more efficient greenhouse. But, again the blocking of the main heat redistribution process - convection - in a fluid is of prime importance. The simplistic greenhouse w/in a greenhouse model above is basically the applied use of insulated double glazed panels which reduces the conductive and radiative losses further. Vsmith 12:26, 18 Mar 2005 (UTC)

We're discussing the mechanism of how the greenhouse works. A greenhouse does not work by insulation any more than a refrigerator works by insulation. Obviously insulation keeps it from becoming the same temperature as the environment, and I have clearly stated that in the description given, but it does not WORK by insulation, since insulation cannot induce a temperature difference. This is central to the laws of thermodynamics. If insulation can produce a temperature difference, then this leads immediately to the creation of a perpetual motion machine. — Cortonin | Talk 21:10, 18 Mar 2005 (UTC)

(William M. Connolley 13:27, 18 Mar 2005 (UTC)) Cortonin - please do not issue patronising instructions such as "do not revert", unless you intend to follow the same principles yourself. I suggest you read the references that I have provided, that specifically address the question "is the GHE a misnomer"? They all answer: yes, it is a misnomer. You have not provided a single reference that addresses the question and provides a different answer. BTW, we're not talking about nighttime, but daytime.

Who says, "This is not a misnomer," using the word "misnomer"?

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) Are you having trouble reading? Piexoto and Oort do. The others do, in equivalent language: Greenhouse effect: the effect of the atmosphere in re-readiating longwave radiation back to the surface of the Earth. It has nothing to do with glasshouses, which trap warm air at the surface. Please stop wriggling.

Are YOU having trouble reading? I wrote, 'Who says, "This is not a misnomer," using the word "misnomer"?' In other words, the only people who would use the word misnomer are those who for some reason think it is, so if you only accept sources which contain the word "misnomer", then clearly you are going to only get one very narrow (and physically invalid) view. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

The references do not say "misnomer" because there is no misnomer. Many of them do say "similar", "resembles", etc, or otherwise make it clear that the two are analogous. And more importantly, the references I have given state clearly how the mechanism works. I will quote to assist you in your reading: — Cortonin | Talk 21:10, 18 Mar 2005 (UTC)

• "The hot surfaces radiate in the infrared (they are hot enough only to send out wimpy photons). The photons, however, do not readily pass through the windows. The heat cannot get out efficiently. A key aspect here is that the photons bringing in the energy (visible light) are a different wavelength than the infrared photons taking it out. Greenhouse glass lets one in but not the other out." [8] (an Earth Sciences textbook which describes the mechanism clearly).

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) The above is true, but is not the mechanism that warms greenhouses.

It is the only mechanism which does work. ("Work" is being used here in the physics sense of a system doing work.) — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

• "Likewise the light impinging on the earth that is not reflected back into space also ends up as heat. All matter re-radiates heat, mainly in the infrared part of the spectrum. Glass, however, is relatively opaque to infrared. Thus the greenhouse glass acts as a one-way energy valve." [9]

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) Indeed it does. But its not the major process.

The references given, and the principles of thermodynamics, disagree with you. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

• "This process is referred to as the ‘greenhouse effect because, in some respects, it resembles the role of glass in a greenhouse." [10]

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) Careless language.

The language is correct. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

• "This phenomenon, often called the greenhouse effect, works in much the same way as the glass panes of a greenhouse. In a greenhouse, electromagnetic energy in the form of visible light is able to pass through the glass and enter the building. The visible light strikes objects inside the greenhouse, and these objects at least partially absorb the light. Some of this absorbed energy is re-radiated as infrared light, which is reflected back into the building by the glass, thus keeping the greenhouse warm. In a similar way, the transmission spectrum of the atmosphere is an important factor in determining the global temperature of the Earth." [11] (A spectroscopy research group. This is directly on topic with "what they do", and their understanding is solid.)

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) Without doubt their understanding of spectroscopy is good, but not their understanding of climate/greenhouses.

Anyone with a background in spectroscopy should be more than qualified to assess the significance of the contribution of thermal IR absorption to the thermodynamic properties of a greenhouse. The greenhouse effect is all about spectra and spectral properties of substances, so certainly they would understand this. It's their field. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

Now, I have clearly shown that prominent references support the correct operation mechanism of a greenhouse by thermal IR absorption, and that they directly relate this as analogous to the global greenhouse effect. — Cortonin | Talk 21:10, 18 Mar 2005 (UTC)

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) Nope, you've failed to find a single published reference.

I showed you a journal article on greenhouse surface design, an earth science textbook, an MSC article, and a page by spectroscopy experts, all of which explicitely support the mechanism of greenhouses as due to thermal IR absorption. I also provided a detailed explanation of the physics involved many times over, which you either failed to understand and are too proud to ask a question about it, or failed to even consider. This isn't even close to disputable science, it's elementary thermodynamics. Why you're still arguing about it baffles me. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

Let's compare this to the opposing quote, "heating in the usual greenhouse is due to the reduction of convection" from Jose Peixoto. No well-educated physicist would write this, so I can only assume his background is something else. I cannot find much reference to him on the web outside of that book. I do see a Jose Peixoto whose background is literature who is considered to be a good writer, but I cannot tell if this is the same one. Reducing convection does not do any work, and thus will not produce a temperature difference. If the authors of a text do not understand this, then that text should probably not be used for anything of great physical importance. — Cortonin | Talk 21:10, 18 Mar 2005 (UTC)

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) Sneering at Piexoto and Oort will merely earn you contempt from and climatologist.

There is also a quote from Idso, who is the president of co2science.org. I thought you were calling this site too dubious to use the other week, but whatever.

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) Your inability to read continues. I'm not quoting from his dodgy site, but from a book.

Why do you always accuse others of being unable to read? It's a ridiculous ad hominem. My reading comprehension skills are just fine, as are my analytical skills, thank you very much. A book authored by SB Idso is obviously the same author as texts authored by SB Idso on that website. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

The Idso quote is unfortunately not very specific. It only says the two are "not analogous", and doesn't explain the reasoning. This hardly trumps a weight of authoritative references which call it analogous and then proceed to describe the mechanism. — Cortonin | Talk 21:10, 18 Mar 2005 (UTC)

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) Your refs are not in the least authoritative: not one is published. And more, not a single one has done what mine do, which is to consider the question of whether it is a misnomer or not. You cannot find a single ref to say: some consdier it a misnomer, but it is not.

It's probably the case that none of the authors of the sources I quoted from would consider the idea that greenhouses work by convection suppression serious enough to even mention. From thermodynamics we know better than to consider convection suppression a source of heating, because it does not do any work. We also know the IR properties of the materials used in greenhouses, and we know that they are transparent to the primary solar region, and absorbant in the primary thermal region. We also know that the thermal flux balancing equations which tell you the resultant temperature (see Kittel and Kroemer for a simple description of how this is done) show the effect that this thermal IR absorbance has on temperature. There is no room for dispute since this is just basic thermodynamics, and so there are no papers being published which focus on this issue. There are only publications which mention it in passing, which I have provided, and textbooks (such as the Earth Science one I posted) which describe the mechanism. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC) (The strike out is because I found a paper, I just had to go back about 14 years for it. See below. — Cortonin | Talk 23:05, 20 Mar 2005 (UTC))

I believe much of the confusion may come from the "blanket myth" that people have. Based on our everyday experiences, people somehow believe that a blanket will warm things and wind will cool things. This is not true, however, but is simply based on our normal experiences as a warm-blooded creature whose body temperature is higher than the environment. If you use a thermometer to measure the temperature of a room, it will give you the same temperature whether or not you have a fan blowing air over the thermometer, because convection will NOT cool the thermometer. This violates the intuition of many people, but that's how thermodynamics works. — Cortonin | Talk 21:10, 18 Mar 2005 (UTC)

So you wanted to debate on the issue of references, and I have done so.

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) Indeed you have, and you've lost.

This isn't win or lose, and your little war-zone mindset is not helping. This is science, and I'm trying as patiently as humanly imaginable to explain it to you. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

Now, perhaps we can return to the simple physics. Suppression of convection cannot explain the greenhouse-in-a-greenhouse.

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) We're not talking about that system! Please don't be silly: stick to the question we're actually talking about.

A greenhouse in a greenhouse is just another greenhouse. If a greenhouse-in-a-greenhouse warms up, then obviously the mechanism that warms greenhouses also works for greenhouses inside of greenhouses. And that is precisely the point of bringing up that system in order to more clearly explain it to you. Please consider it and try to understand what I'm saying about that instead of summarily dismissing it. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

I asked you to consider that simple system, as this would probably end the revert war if you were to do so. The goal of consensus on Wikipedia is for arguments to converge on a single presentation by careful and open consideration of the ideas by the editors. So please take a few moments in your mind to examine the physics of a greenhouse-in-a-greenhouse. — Cortonin | Talk 21:10, 18 Mar 2005 (UTC)

(William M. Connolley 21:35, 18 Mar 2005 (UTC)) At the moment, my answer is above. Why don't you however take a few moments to provide refs.

I did. Now please consider the physics of a greenhouse-in-a-greenhouse, and how that relates to the physics of a greenhouse. — Cortonin | Talk 00:22, 19 Mar 2005 (UTC)

Convection model: Greenhouse B, the inner one, is better insulated from the outside world by outer Greenhouse A. While both are being irradiated, A is losing heat to the cooler outside world and is thus cooler than B which is losing heat to the warmer inside of A. When neither is irradiated, A is losing heat to the cold outside world, while B is being kept warm by A and is losing less heat to it. If A and B are for some reason at same temp when not irradiated, B will only be cooled after A gives up heat to the outside world. Volume and surface area issues ignored. (SEWilco 09:11, 21 Mar 2005 (UTC))

Now answer one question: Why is the outside world colder? It is also being irradiated by the same amount, in this model. Is the outside colder because it's windy? Wind doesn't make a system colder, it only transfers heat from one place to another. Experimentally we see that a well insulated greenhouse is sometimes heated by higher wind, and sometimes cooled by it. — Cortonin | Talk 10:04, 21 Mar 2005 (UTC)

Radiation model: Greenhouse B, the inner one, warms at the same rate as A if thermal radiation enters without loss through two transparencies, if all radiation leakage is blocked by a single layer. Volume issues ignored. Losses due to conduction ignored. (SEWilco 09:11, 21 Mar 2005 (UTC))

The thermal IR is not perfectly blocked. I've seen typical values for a greenhouse at around 25% to 60%, but not completely. — Cortonin | Talk 10:04, 21 Mar 2005 (UTC)

Good air model: Greenhouse B, the inner one, has better protection from outside bad air and the life forces inside thrive better and produce more cheery warmth, and rosier cheeks on the gardeners. See also: Maxwell's demon (SEWilco 09:11, 21 Mar 2005 (UTC))

• chuckle*  :) — Cortonin | Talk 10:04, 21 Mar 2005 (UTC)

Doesn't anyone around here have some thermometers, glass, and enclosures? Give me a Hummer and a BMW Mini to park inside it and I'll run some tests. (SEWilco 09:11, 21 Mar 2005 (UTC))

The technique is used regularly by gardeners, as I mentioned above. But if you do try an at-home test of a jar in a jar, make sure both have a little bit of dirt or something in them to absorb the light. Otherwise you're basically just making an unusually shaped lense.  :) — Cortonin | Talk 10:04, 21 Mar 2005 (UTC)

Horticern

Well, I dug around quite a bit, and going all the way back to 1991, I was able to locate a paper which models the operation of a greenhouse in excruciating detail. Anyone interested in the detailed 30 page thermodynamic description should read the following paper. — Cortonin | Talk 11:18, 19 Mar 2005 (UTC)

"Horticern - An Improved Static Model for Predicting the Energy-Consumption of a Greenhouse"

Jolliet O, Danloy L, Gay JB, Munday GL, and Reist A

Agricultural and Forest Meteorology 55(3-4): 265-294 Jun 1991

It describes the complete mechanism of energy exchange in a greenhouse. Of relation to the discussion here, it describes that for a well insulated greenhouse, the influence of sky temperature is much higher than wind speed. It also describes how, for a well insulated greenhouse, convection can actually increase the temperature of the greenhouse (as I was explaining earlier). Convection only serves to bring the temperature of the outside surface of the greenhouse into equilibrium with the outside air, but in conditions of a well insulated greenhouse, the outside of the greenhouse can be cooler than the inside of the greenhouse and the outside air due to radiative thermal exchange with the sky (since the inside is radiatively isolated), and as a result, greater convection (more wind) can actually contribute more heat. It also explicitely shows the significant impact that adding extra glazings (which reduce thermal IR escape) has on the thermal loss of the greenhouse. — Cortonin | Talk 11:18, 19 Mar 2005 (UTC)

In summary, it shows explicitely and in excruciation detail that greenhouses operate by a radiative imbalance, the significance of radiative exchange to the function of greenhouses, and that convection only serves to bring the temperature of the outside surface of the greenhouse into equilibrium with the outside air, which sometimes cools and sometimes warms the greenhouse. This model is thoroughly confirmed by rigorous experiments, and should be considered fairly concrete and accurate. — Cortonin | Talk 11:18, 19 Mar 2005 (UTC)

The level of mechanistic detail and experimental confirmation in this paper should clear up any lingering confusion regarding this edit war. — Cortonin | Talk 11:18, 19 Mar 2005 (UTC)

(William M. Connolley 21:53, 19 Mar 2005 (UTC)) Thats nice. I'll see if I can find a copy. Given your previous problems with paper content, though, I won't be taking your word for it.

Or you could stop the baseless personal attacks [12], get the article, and read it. I spent a long time searching for that article, solely for the purpose of explaining the matter to you. So you can stop the petty insinuations about my incompetence and go read about the mechanism for yourself. — Cortonin | Talk 07:21, 20 Mar 2005 (UTC)

(William M. Connolley 20:37, 20 Mar 2005 (UTC)) You seem to be unable to distinguish between people pointing out errors in your refs (mesospheric water anyone?) and personal attacks. I'll look up the paper; until then I certainly don't intend to trust your summary of it, given your biased summaries over at global warming. Note, BTW, that you have earlier indicated unwillingless to look up the references I've provided.

You have indicated that the references you gave provided no mechanistic detail, so there is no point in locating those texts. I instead spent time looking for texts which DO describe mechanistic detail, since that is the dispute at hand, and found this article to be the most comprehensive. While it is completely unrelated to this topic, I consider the work on mesospheric water vapor and its atmospheric chemistry effects informative and relevant to a complete understanding of the system, and your continued personal attack about this indicating something about my credibility is simply an ad hominem. — Cortonin | Talk 22:25, 20 Mar 2005 (UTC)

(William M. Connolley 11:34, 21 Mar 2005 (UTC)) Your inability to understand the difference between tropospheric and mesospheric water vapour does you no credit. You are stubbornly clinging to your mistake, which does your credibility no good.

Uh, first, water vapor is water vapor. The difference would be altitude, concentration, and quantity, but it's the same compound. I do understand the difference between the troposphere and the mesosphere, and this is not particularly complicated. The only "mistake" is a strawman you have created in which you say I have somehow claimed that the troposphere and the mesosphere are the same thing, when in reality, you are the only one who has been talking about this. How this can be a misunderstanding on my part, when I have made no claims about it, is beyond me. — Cortonin | Talk 21:24, 21 Mar 2005 (UTC)

(William M. Connolley 23:55, 21 Mar 2005 (UTC)) The mesosphere is terribly terribly thin. Stop digging yourself this silly hole.

This has nothing to do with bias, and there are no political issues involving the mechanism of gardening greenhouses. This only has to do with correct scientific description, and with ego. Correct and thorough scientific description is found by reading the source I gave. Ego has to do with edit warring to avoid having to admit to being wrong, and this is extremely unproductive for Wikipedia. — Cortonin | Talk 22:25, 20 Mar 2005 (UTC)

Once again, READ THE PAPER RATHER THAN EDIT WARRING!!!!!! I provided you with a clear and unambiguous source which describes the mechanism in excruciating detail, and your chosen course of action is to continue edit warring based on not trusting me? This is completely against all Wikipedia intents and policies of good faith and mutual cooperation. Stop it, read the paper, understand the mechanism, and stop reverting to the physically invalid description. — Cortonin | Talk 22:25, 20 Mar 2005 (UTC)

(William M. Connolley 11:34, 21 Mar 2005 (UTC)) So, I must read your paper but you won't bother read my refs? I must stop reverting to my version but you continue to recert to yours? Your total lack of understanding could not be plainer.

Provide a reference which describes the mathematical details of a mechanism for convection suppression as a mechanism for greenhouse operation, and compares this to experiment, and I will gladly read it. You have not yet provided such a reference. I HAVE shown such a reference which shows the mechanism for heating is thermal IR absorption. If you can provide such a reference showing that level of detail, then like I said, I will read it. Now, will you read mine since I already provided it? — Cortonin | Talk 21:24, 21 Mar 2005 (UTC)

Notice how this argument is going, I'm calling for you to read a paper describing a mechanism, and you're just insulting me and saying I don't understand. Which approach sounds more scientific to you? — Cortonin | Talk 21:24, 21 Mar 2005 (UTC)

(William M. Connolley 23:55, 21 Mar 2005 (UTC)) Provide a reference that specifically deals with the point at issue: is the greenhouse effect a misnomer. I've done that; you've refused to read them. I'll do my best to read yours (independent of your bad faith in not trying to read mine).

What the??? The issue is not "Is the greenhouse effect a misnomer?" The goal is to correctly describe the mechanism of how greenhouses operate. Is the greenhouse effect a misnomer? In what way? The sky is not made of glass, the sky is not a giant building made by man... There are a dozen different ways a person could consider it a misnomer if they so choose, because obviously they are not the same system and not composed of the same parts. But the point is, the underlying MECHANISM of the heating effect is the same in both systems, and this is thermal IR absorption. — Cortonin | Talk 08:47, 22 Mar 2005 (UTC)

Stop!

Both revert warriors are at fault. They are each partly right and wrong. You both need to just back away for a bit and let some 3rd party come up with a compromise containing the good points of each. I can give it a try later as I think I can tie both viewpoints together for a compromise, but C and WMC must agree to stop the silly reverting. Vsmith 16:31, 22 Mar 2005 (UTC)

(William M. Connolley 19:45, 22 Mar 2005 (UTC)) OK. For my part, I'll give you a chance to improve things.

I made an attempt to merge the "misnomer" concerns with the correct mechanism description, with the most accurate possible description of its "misnomer" status with regard to convection. I'm not sure what educational value this has, but if people like to throw around the word "misnomer", then so be it. My only concern is that the physics is described correctly in the process. Hopefully this will remedy the situation. — Cortonin | Talk 20:47, 22 Mar 2005 (UTC)

You can grow fruit in a good solar-only greenhouse in the winter at the U.S./Canada border. This extreme difference is not caused by the wind not blowing inside. The mechanism of greenhouse operation is described in the literature, and reflected here in more digestible form. — Cortonin | Talk 20:47, 22 Mar 2005 (UTC)

Good grief! That attempt to merge the "misnomer" concerns with the correct mechanism, was basically simple trolling for a negative response. We've got to do better than that. Vsmith 05:09, 23 Mar 2005 (UTC)

Or you could try assuming good faith, rather than calling me a troll. — Cortonin | Talk 11:47, 23 Mar 2005 (UTC)

My proposal would be a considerable re-write focusing on the mechanisms involved, focusing on heat or energy transfer and/or blocking. Now the kicker, I plan to list the results of my rewrite for peer review or whatever fits and ask both of you two warriers to leave it be for a period of time. Comments here would of course be acceptable, especially if I make some gross error or another. :-) Vsmith 05:09, 23 Mar 2005 (UTC)

First draft done - probably will do some revising (I'm tired now:-). I have kept the refs that both listed. However, I don't have access to those not online. I have left out some of C's inline refs that seemed questionable to me, may include some later after more reflection. Vsmith 05:09, 23 Mar 2005 (UTC)

That's a good start. I made a few fixes here and there and threw in some more detail at a few spots. — Cortonin | Talk 11:47, 23 Mar 2005 (UTC)

Thought this would occur, as I didn't include all of your "preferred" text. However, the object is to stop a silly revert war between you two. Now I will consider your suggestions and include what I see as reasonable. In the meantime, the deal is "leave it be" and discuss. Your edits were heading for a piecemeal reversion. Or do you simply want another revert war? Am I just wasting my time? Vsmith 12:34, 23 Mar 2005 (UTC)

If you're just going to revert all 10 of my edits, then you have already started a revert war. You think that didn't take any of MY time? This idea you've come up with of reverting other people's contributions until you have a chance to come along and "consider" them is not how wikipedia works. — Cortonin | Talk 21:50, 23 Mar 2005 (UTC)

You were involved in a pointless revert war. I am trying to halt that and come up with an acceptable version. I requested that the two involved in the war stand back a while and observe as I and other editors, hopefully, can put together a reasonable article. If you insist on taking over and pushing in your POV (the reason, or half of, the edit war) with a gradual stepwise revert then it won't work. I am aware that you object to some of the emphases I have put on different aspects here. So back off a bit, there is no hurry, Wikipedia is in no hurry. Vsmith 23:58, 23 Mar 2005 (UTC)

The ref. [13] contains the following quote There are other potential greenhouse gases, such as carbon dioxide and methane, but their atmospheric concentrations are so low that they may be ignored (CO2 at 0.033% and CH4 at 0.0002%). In view of that absurdity I think we can leave that one out.

For the purposes of considering the first order description of the static greenhouse effect, which is what's being described, that statement is correct. — Cortonin | Talk 21:50, 23 Mar 2005 (UTC)

First order ... correct? Don't think so and don't need it. Vsmith 23:58, 23 Mar 2005 (UTC)

The other added ref. [14] contains a simple erroneous statement The fact that water vapor, carbon dioxide, and other gases reflect infrared light is .... This error makes it dubious in this context. So let's leave it out. Vsmith 18:16, 23 Mar 2005 (UTC)

If the reference were a wiki page, I'd probably swap "reflect" for "absorb and reemit" for clarity of mechanism, but the word "reflect" is simply used to describe the flow of energy. It's a shorthand. — Cortonin | Talk 21:50, 23 Mar 2005 (UTC)

The section in question is a small part of a quite good discussion of spectroscopy. The small section in question is a side issue for them and as it is stated in error whether shorthand or not makes the ref questionable for this article. Vsmith 23:58, 23 Mar 2005 (UTC)

Well if you're going to start removing references with imprecision in their language and statements that you find physically imprecise, then we're going to do it across the board. Wood 1909 is a poorly done and uncontrolled experiment designed to disprove the existence of a greenhouse effect, and the experiment has long since been replaced by more scientific work. Idso just has nothing to do with the page, since it has no technical information which has been presented about how solar greenhouses operate. And Piexoto's description of greenhouse operation is physically invalid (for saying that reducing convection produces heating) and it directly contradicts the rigorously experimentally confirmed models found in the literature. — Cortonin | Talk 07:07, 24 Mar 2005 (UTC)

(William M. Connolley 20:27, 23 Mar 2005 (UTC)) Thanks to Vsmith for the compromise. numberwatch is a septic site I've seen before. For example http://www.numberwatch.co.uk/Temperatures.htm provides us with the std.septic quote the satellite record is relatively short, as the technology has not been around for very long. It shows a slight cooling trend (the page is dated april 2004).

Convection

Convection is NOT the dominant heat mechanism for a greenhouse. First, suppression of convection does not ever generate heat. Second, even if convection is low, such as in the case of low wind speed, the greenhouse heats significantly. In fact, a well insulated greenhouse does not heat up much more or less when the windspeed is high (see Horticern paper), which shows that convection is not significantly changing the temperature difference between the inside and the outside of the greenhouse, which shows that the localized outside air temperature is not being changed much by localized outside convection, and thus its suppression is not significantly contributing to the heat difference. — Cortonin | Talk 07:46, 24 Mar 2005 (UTC)

No one said that covection is a heat mechanism, dominant or otherwise. You ar either mis-reading or simply trying to find an excuse to revert. The only heat source in the greenhouse is the incoming solar radiation and the absorption of it. Convection, conduction, and secondary radiation are only heat transfer mechanisms that move heat around within and eventually out of the structure. I have no clue why you keep switching the discussion from the blocking of convection by the glazing to something rather irrelevant about outside wind speed. Localized outside convection is irrelevant and not mentioned in the article. Vsmith 14:16, 24 Mar 2005 (UTC)

Because if you want to experimentally measure the effect of convection, you do it by isolating that variable. This means you consider the changes to the temperature difference under various wind speeds. AND, when that is done, as it is explicitely done in the Horticern paper, it is found that in a well-insulated greenhouse, the contributions of convection are small. Sometimes convection removes heat energy from the greenhouse, and sometimes it ADDS heat energy to the greenhouse since the very outer surface of the greenhouse can actually be cooler than the air around, due to its radiative coupling with the upper sky. — Cortonin | Talk 19:57, 24 Mar 2005 (UTC)

Well I'll be... Can you stay with the program. We are not discussing convection outside of the greenhouse, we are talking about the simple concept that heat is retained within the greenhouse because the air inside cannot convect away and take the heat with it. What is so difficult about that simple fact? If I want to keep my house warm in the winter, I don’t leave the door open. Vsmith 02:43, 25 Mar 2005 (UTC)

Convection outside IS what you're talking about, you just haven't realized it yet. In your model, there are two systems. System A, the outside, has incoming solar radiation striking the ground, and convection with surrounding areas. System B, the greenhouse, has incoming solar radiation striking the ground, and no convection with surrounding areas. Then what you are saying is that the lack of convection allows system B to become hotter than A. What this statement really is, is a backwards way of formulating the statement that the convection in system A cools it. So we are INDEED discussing convection outside, and the question at hand is whether wind outside produces a cooling effect to the outside. The answer is, not always, and not significantly, and it is covered in the Horticern paper. — Cortonin | Talk 10:46, 25 Mar 2005 (UTC)

There are indeed three mechanisms for heat redistribution, convection, conduction, and thermal IR. When convection is stopped, and conduction is reduced by a well-insulated barrier (a prerequisite for having a thermodynamically isolated system), then you can see the results of thermal IR imbalancing most effectively. At this point you find out (by measuring, as pointed out above), that the temperature increases produced by thermal IR absorbtion far exceed the contributions of convection to the external atmospheric temperature. See, the outside also has three mechanisms for heat removal, convection, conduction, and thermal IR. The outside does not have the thermal IR barrier of the gardening greenhouse, and so the outside air couples with the upper sky (which can be pretty far below freezing) through thermal IR exchange, and this lowers the temperature of the outside in a way that the greenhouse does not experience. (Compare a cloudy night and a clear night, and the greenhouse's absorption can significantly exceed this.) And if you don't trust the thermodynamics, then convection's effects on the relative temperatures can be measured by correlating temperatures with windspeed, and when that's done, the results show what I have stated (see Horticern). — Cortonin | Talk 20:53, 24 Mar 2005 (UTC)

Twice now I've had to correct the statement "In the global greenhouse effect the major thermal control is the infrared absorbent effect of the greenhouse gases." This is where the role of convection IS significant, but it is being underplayed in the article. Still, in the global greenhouse effect the major mechanism for the effect is IR absorbence, but the major "thermal control" is actually large-scale atmospheric convection. Examine the numbers in that paragraph for the temperatures that would exist with no greenhouse effect, with a convectionless greenhouse effect, and the temperatures that actually exist. Those numbers show that large-scale atmospheric convection is present and acting as a significant thermal control. Note that the difference in scale between the two systems is a contributing factor to the different role convection has. — Cortonin | Talk 07:46, 24 Mar 2005 (UTC)

Twice now you have tried to distort the statement ... Of course convection is significant in the atmosphere - think weather, but it is not the significant part of the global greenhouse effect, don't know where you are trying to go with that - confusion of the issue, maybe. Vsmith 14:16, 24 Mar 2005 (UTC)

Convection is not a part of the "global greenhouse effect", because convection has nothing to do with the greenhouse effect, but global atmospheric convection DOES reduce OVER 50% of the warming due to the greenhouse effect. (Check the numbers in that paragraph.) It is not quite right to say that something is the "major thermal control" when over half of its contribution is erased by something else. — Cortonin | Talk 19:57, 24 Mar 2005 (UTC)

And lastly, the greenhouse-in-a-greenhouse is NOT convection based. Not only does convection not produce heat, and not only is there very little convection within a greenhouse to begin with, but that's not how they're designed. I've fixed this twice already. Take a look here for a typical example of the films you would use in a greenhouse. Note that different glazings are available with different optical properties, for neutral, for cooling, and for heating, based on the requirements of the grower's climate. If you want more detail about the operation of these films, read here. I don't know how to make it any more clear. — Cortonin | Talk 07:46, 24 Mar 2005 (UTC)

Duh - anything that stops heated air from rising and thus keeps it confined to a localized area is convection based by limiting or impeding convection. Again you try to imply that I'm saying convection produces heat - nonsense, see above. And the plastic sheeting - no matter how it's designed and advertized - doesn't produce heat either, you are starting to sound like a high-tech greenhouse glazing promoter here. The gh in a gh is convection based by limiting convection. Vsmith 14:16, 24 Mar 2005 (UTC)

?? The plastic sheeting yields measureably DIFFERENT temperatures based on the thermal IR coating placed upon it. Based on the coating type selected, the temperature can be made greater than, equal to, or less than the outside temperature, clearly indicating a wide range of temperature selections which have nothing at all to do with convection. Greenhouse experts disagree with you. Greenhouse manufacturers disagree with you. Greenhouse glazing sheet and panel manufacturers disagree with you. The researchers publishing papers about finding new materials to make greenhouses out of disagree with you. The researchers publishing papers modeling the way a greenhouse works and then comparing this to experiment disagree with you. And you have presented no detailed physical model to contradict the weight of these people. I assume you know how to do a literature search, so I'm going to ask you to not revert back to the convection-dominant version without presenting a detailed study which outlines a physical model for convection suppression as a mechanism for greenhouse operation, has equations representing this, and preferrably compares this result to experiment. It's the least you could do. I've spent countless hours here explaining the physical model and digging up sources to explain the mechanism here, and apparently it's being dismissed as commercialism somehow? So if you somehow think there's all this science out there which supports convection suppression, then you go find it. You get that model description which says convection suppression is how a greenhouse works, writes equations describing it, and compares it to experiment, and then you present it here. Otherwise this entire convection argument is just a bunch of... convection. — Cortonin | Talk 19:57, 24 Mar 2005 (UTC)

Well, I'll be again... wasn't that a lot of blather! Why don't we start with some common sense (a scientifically risky place to start, but...). Greenhouses were in use and working quite well before the existence of plastics or all this high-tech coating stuff (I'll admit my ignorance here and note that I exist in a rural area without easy access to all that scientific research and industry hype). My grandfather used greenhouse technology in northern Minnesota almost 100 years ago. So why don't we at first stick to the fundamentals of a simple greenhouse as it would have worked then. In future sections we can add all the high-tech plastics and coatings which appear to be obscuring your understanding of the basics I'm trying to focus on. Then you can perhaps expound on heating a greenhouse with moonlight :-) Vsmith 02:43, 25 Mar 2005 (UTC)

The answer to that is that glass behaves the same as the plastics with the IR absorbant coating. I'm trying to explain it to you in terms of the more advanced materials, because this should make it clearer what the actual cause for the effect is. If you can explicitely manipulate one, and only one variable, namely the optical properties of the glazing, and in doing so change the resulting temperature, then you have isolated the mechanism of operation. — Cortonin | Talk 10:46, 25 Mar 2005 (UTC)

(William M. Connolley 11:37, 25 Mar 2005 (UTC)) Cortonin, please stop behaving so badly. You write: So if you somehow think there's all this science out there which supports convection suppression, then you go find it. These is no need for Vsmith to find it, because I've added the refs/links already. Now stop playing around: if you won't accept compromise, I'll start rv'ing to my version rather than Vsmiths.

First, I don't think threats are proper wikiquette. Second, I have not seen any articles put forward by anyone which describe a detailed mechanism for greenhouse function by convection suppression. There is however a detailed description of greenhouse function showing its IR absorbent nature in the Horticern paper. Have you read it yet? You said you would. — Cortonin | Talk 11:59, 25 Mar 2005 (UTC)

(William M. Connolley 12:16, 25 Mar 2005 (UTC)) It wasn't a threat, it was a promise :-). I would prefer to stick to the Vsmith compromise - but since you wouldn't, I've gone back to my version. As to your ref: yes, its on my list of things to do.

'ell I be - what a fine mess :-)

A rather unfortunate consequence I'd say. If Cortonin could only have backed off a bit and added suggestions here rather than impatiently trying to do a gradual revert this could have been avoided. When someone steps in to try and mediate a dispute the disputees should show a bit of patience and keep a hands off mode for a little while. Cortonin was unable or unwilling to do that. I was still in the process of learning and revising to improve the article and include more discussion of the importance of glazing absorbence, but he was unwilling to let me try to work it out - don't rightly know what the hurry was. I fail to see the purpose of his contrary impatience. Maybe it was just a fishing expedition. Vsmith 13:14, 25 Mar 2005 (UTC)

You made wide sweeping changes to the article, which I then worked with, despite this erasing most of my previous work. (That's how cooperation actually works here.) I took the edits you had made, and I went through them fixing the areas you added which had phrasing problems or physical inaccuracies (and carefully explaining the edits along the way). The ego games that are being played here are ridiculous, with shouts like "fine then I'll revert to my version" or "don't edit my version while I try to figure out how to fix it." Please read Wikipedia:Ownership of articles. — Cortonin | Talk 17:58, 25 Mar 2005 (UTC)

Hmm... Seems there was a revert war and it seems that Cortonin was one of the combatants. I made a silly proposal to try to defuse the war by attempting to write a compromise article AND requested both combatants to back away and hold off editing while I worked on it. Cortonin flat ignored this request or refused to accept the combatant status and immediately began a piecemeal revert to his POV as if a few days delay with my obviously erroneous version was totally unacceptable. How silly of me to try to reach a compromise in view of this kind of arrogant behavior - I'm quite fed up with it. Vsmith 03:43, 26 Mar 2005 (UTC)

Approaches to a question

It seems to me that in thinking about the physics of a garden greenhouse, you can base your assessment of what is going on according to (1) what is providing the influx of energy, and (2) what the necessary conditions are.
Then on to the question: what is the cause of the garden greenhouse being warmer than the garden?
Approach (1) identifies - of course - the solar radiation as providing the influx. Assessment ready, but you're none the wiser
Approach (2) makes an inventory of possible ways of outflux. Radiation loss, conductive loss, convective loss. Thinking it through (or referencing actually performed experiments) is it seen how much energy would be lost if that loss would be maximized. It is observed that maximizing convective loss is more crippling to the garden greenhouse than the other losses.

The aim of the analysis-of-outflux approach is the more informative approach in this case, it is really digging into the question.
The method of the analysis-of-outflux approach is to do the opposite of making the garden greenhouse perform well. The method of the analysis-of-outflux is to do things that are way outside of what you normally do, because they degrade the performance.

It is observed that maximizing radiative loss does not degrade garden greenhouse performence much. But it is easy to get a lot of convective loss, and it renders the garden greenhouse useless. Therefore the analysis-of-outflux approach identifies the suppression of convection as the primary contributor to the garden greenhouse performance.

As far as I can tell Cortonin is arguing that 'opening the windows' is so far outside normal garden greenhouse usage that discussing it cannot possibly be relevant to the question. --Cleon Teunissen | Talk 11:55, 26 Mar 2005 (UTC)

First, trying to analyze the role of convection suppression by opening a bunch of windows is a fallacious approach to the question. If you stick a thermometer in a greenhouse, and try to measure its temperature with the windows open, then you're not measuring the temperature of the greenhouse, but you're measuring the temperature of the air flowing through the greenhouse from the outside. What the point of that is, I have no idea. In thermodynamics, if you're going to have a separate temperature, the initial premise is that you must have a roughly isolated system. This however is merely a prerequisite, and does not tell you the function. The fact that a greenhouse is an isolated system is not its mechanism of operation. That a greenhouse is an isolated system is merely a prerequisite for considering it as a system. — Cortonin | Talk 18:57, 26 Mar 2005 (UTC)

Second, where you have made a critical error is in the statement, "It is observed that maximizing radiative loss does not degrade garden greenhouse performence much." In fact, it is observed that changing the radiative loss changes the greenhouse performance enormously, even to the point of removing it. In fact, if you were to have an insulated greenhouse, with no transparent surface facing the nearby environment, and the only transparent surface facing the sky, with no IR absorbence, then the greenhouse would freeze, as it would promptly couple to the upper sky temperatures which are extremely cold. The outside environment is constantly coupled to these upper sky temperatures at night, mitigated somewhat by the presence of cloud cover, which is why the temperature outside can easily drop 15C or more overnight. The significance of thermal exchange by IR coupling is quite large, so much so that it's part of everyday experience, most people just don't know that's what's causing it. — Cortonin | Talk 18:57, 26 Mar 2005 (UTC)

So if you want to consider the relative magnitude of the effect of "convection suppression", asking the question, "Does opening the window remove the effect?" is most definitely an incorrect question to ask. A long time ago, I made the comparison with an oven. Opening the door to an oven definitively removes the ability of the oven to operate. Try to bake a pie with the door open, and you will fail most miserably. So what is the contribution of convection suppression to the operation of the oven? If you have the heat source of an oven off, it will produce no heat whatsoever, and will simply come to match the temperature of the room. You can suppress the convection in the oven until you're blue in the face, and the oven will still be at room temperature. So how does the oven operate? The oven is an isolated system, with its insulation and isolation from the room, which gives it the potential to operate as a separate system, and then it operates by having a heat source inside. — Cortonin | Talk 18:57, 26 Mar 2005 (UTC)

So now lets compare this to a greenhouse. A greenhouse is an isolated system, with its insulation and isolation from the air, which gives it the potential to operate as a separate system, and then it operates by virtue of its optical properties. If you tweak the optical properties such that a greenhouse's glazing excludes visible and UV while permitting IR to pass, you will have a greenhouse which is COLDER than the outside air, and if you tweak the optical properties such that a greenhouse's glazing permits visible light while excluding IR, then you will have a greenhouse which is WARMER than the outside air. This is essentially a knob which you can adjust to determine the temperature of the greenhouse, from cooler than the environment to warmer than the environment. So a greenhouse then operates by specification of the optical properties of the glazing (where plain glass, for example, happens to do a good job of IR absorption, and thus provides warming). — Cortonin | Talk 18:57, 26 Mar 2005 (UTC)

To say that a greenhouse operates by being an isolated system is as fallacious as to say that an oven operates by being an isolated system. Being isolated is not how it becomes a different temperature, it is only how it is possible to maintain a different temperature by OTHER means. Now, if you want to compare the relative contribution of convection and IR coupling, then the way to do this is to compare their relative contribution to the temperature of the immediately surrounding environment. The way to do this is to vary one property, namely wind speed, and see how this changes the temperature of the outside world, which is still experiencing convection, and the greenhouse temperature, which is mostly isolated from convection (except still experiences some loss through it due to its outer surface). When you do this, it turns out that the temperatures change very little. In fact, sometimes the temperature of the greenhouse actually rises proportionally to wind speed increases, because the outer surface of the greenhouse (where there is no longer any IR absorption) is so strongly coupled via IR to the upper sky that it is actually cooler than the warmer air. — Cortonin | Talk 18:57, 26 Mar 2005 (UTC)

There are two logical errors which I think may be contributing to the mass confusion going on here. The first is the common-experience myth that wind is somehow always a cooling force, which humans come to believe because they have warm body temperatures, so wind almost always cools a human. The second error, is that the "opening a window" question is being considered, while the "swap out the glazings with different glazings" question is being ignored. The reason for this is at best that it's physically easier to open a window, but the fact that this is easier tells us very little. Opening a window will never do more than remove isolation. If you were to swap out the glazing with a different glazing, then you could easily return the temperature to the environment if the material was completely transparent (or even colder if the direction permits coupling to the freezing upper sky). Removing isolation will always cause a system to couple to the temperature it comes in contact. The difference between the two is that convection couples to the surrounding environment, while thermal IR couples both to the surrounding environment AND to the much colder upper sky. This is why the first thing greenhouse growers do to prevent cooling at night is to put a reflective foil over the windows. So now you might be asking why the IR properties should be considered differently from the convective properties if they both couple to something. The answer is simple. The question of concern is, "How does a greenhouse attain a different temperature from the immediately surrounding environment?" Convection suppression does not do this, that only makes it an isolated system, but will never PRODUCE a temperature DIFFERENCE by the laws of thermodynamics. What then provides an external force, is the optical property of the glazing. Let's consider a greenhouse right after sunset, where the windows were wide open and the temperature is equal to the outside environment. Now, we close the windows to make the greenhouse an isolated system. So there is no longer any solar input to change the temperature, and it is currently the same as the outside temperature. But as the night progresses, the temperature becomes different fromt he outside temperature. The outside environment is cooling off, it's coupling to the upper sky and losing heat like crazy, while the greenhouse is IR isolated, and maintaining its heat much better. There is no difference between the two systems at start, no solar contribution to the equation, and the only difference is that one is IR absorbent. That is how a greenhouse functions. When you add the sun to the equation, the sun contributes energy roughly equally to the outside and to the greenhouse (and usually slightly less to the greenhouse), and so it does not provide any difference in heating to the outside or to the greenhouse. The only difference is that the greenhouse is not leaking energy as profusely into the upper sky by thermal IR, and so it maintains more of the energy that the outside throws away. — Cortonin | Talk 18:57, 26 Mar 2005 (UTC)

---

Cortonin | Talk 18:57, 26 Mar 2005 (UTC) it is observed that changing the radiative loss changes the greenhouse performance enormously, even to the point of removing it. [...] if you were to have an insulated greenhouse, [...] with no IR absorbence, then the greenhouse would freeze, as it would promptly couple to the upper sky temperatures which are extremely cold. Cortonin | Talk 18:57, 26 Mar 2005 (UTC)

Hmm, that scenario would indeed maximize radiative loss. Usually a garden greenhouse is situated in a garden. The garden, being at ambient temperature, irradiates the greenhouse with ambient temperature IR. The garden greenhouse, being somewhat above ambient temperature, has overall just slightly more outflux of IR than influx. On the other hand, a garden greenhouse in a shaded valley on the Moon would hardly be irradiated by the environment, and it would itself radiate out in accordance with its own temperature.

So, my dear Cortonin, I do grant you that garden greenhouses perform the way they perform because they are not situated in a shaded valley on the moon! --Cleon Teunissen | Talk 19:53, 26 Mar 2005 (UTC)

You missed the part that said "sky". When a greenhouse is situated in the middle of a garden (on Earth), the outside parts of the garden are losing energy in huge quantities to the sky (which on a clear night is about 25C cooler than the ambient temperature). The greenhouse, however, does not, due to its IR absorbence, which keeps it warmer. The "freeze" example was for a system with no IR absorbence, IR coupling only to the sky (by having windows only pointing in an upward direction), and insulated from the environment. This has nothing to do with the Moon, which would have a sky temperature of around 3K (the radiation temperature of space). — Cortonin | Talk 22:07, 26 Mar 2005 (UTC)

You should read the Horticern paper in the references. The sky interaction is explained in there. — Cortonin | Talk 22:07, 26 Mar 2005 (UTC)

I'd like to take a step back.
I have an example of a question that, I think, has parallels with the garden greenhous question. I live in the Netherlands, the country known for its polders. What is the primary agent in maintaining an agreeable ground water level in the polders? Well the drainage pumps (hundreds of windmills in the past, nowadays a couple of huge diesel-engine powered stations) are pumping out water whenever necessary. The pumps are doing the work. Then again, one can argue that it is the dikes that keep the water at bay in the first place. So, do I want/need to categorize the dike as a prerequisite, or as a contributor? Well, hey, any prerequisite is effectively a contributor, and any contributor is effectively a prerequisite.
Interestingly, having a dike is physically a contributor and conceptually a prerequisite; conceptually, there is no such thing as a polder-without-a-dike. What I would prefer is that conceptual demarcations are not invoked as evidence in a discussion of the physics of a phenomenon. --Cleon Teunissen | Talk 08:25, 28 Mar 2005 (UTC)

Very good! Of course the dikes are irrelevant - just isolating boundaries - it's really them high tech pumps that keep your feet dry :-) -Vsmith 14:53, 28 Mar 2005 (UTC)

I'm considering another angle. A pressure cooker. The taters are ready faster because..??
Well, like in the example of an oven, things get cooked because they are heated, so that looks like the primary cause of the pressure cooker effect', heat is transferred to the cooker. Then again, it could be argued that the sealing of the pressure cooker, preventing equalisation of pressure with ambient pressure has something to do with it. Now, I concede that when you remove the lid of a pressure cooker you remove the very thing that defines it's being a pressure cooker; remove the lid and the thing ceases to be a pressure cooker. Nonetheless, I am inclined to state that the the lid sealing the cooker is the primary contributor to the pressure cooker effect. --Cleon Teunissen | Talk 15:17, 28 Mar 2005 (UTC)

If you plug in a pressure cooker but don't seal it, then it's not a pressure cooker, it's just a cooker, but it is operating. If you unplug a pressure cooker and seal it, then it's a pressure cooker, but it's not operating, EVEN THOUGH it is sealed. The system operates by the aspect which is doing work. — Cortonin | Talk 02:09, 29 Mar 2005 (UTC)

History of the Pressure Cooker
In the USA the first pressure cooker patents were granted in 1902.

Hi Cortonin, when those patent applictions were filed, what do you think the designers wrote up as the main feature of the pressure cooker? Do you think they wrote in the patent application:"The pressure cooker is a pan with a lid. It cooks the food because it is being heated by the stove." Do you think they used words to that effect? In your opinion, should they have used wordt to that effect? --Cleon Teunissen | Talk 15:32, 29 Mar 2005 (UTC)

I wouldn't choose your words, but I should hope they somehow distinguished the pressure cooker from other assorted sealed containers which are not for cooking. Isolation never produces a thermodynamic difference, something has to come along and make that difference. A greenhouse can be made hotter than the surrounding environment OR COOLER than the surrounding environment, simply based on adjusting the optical properties of the glazing. All convection will ever do is act to equalize it to the ambient temperature, whether above or below the temperature in the greenhouse. Convection, just like conduction, is not a directional force, it only equalizes with the ambient temperature. IR absorption is definitively different because the IR radiation is not just coupling to the ambient temperature, but coupling the ground surface and the inside of the greenhouse to the sky, where the temperatures are much much cooler than the ambient temperature. Radiative coupling to the sun raises the temperature of a greenhouse, and radiative coupling to the sky lowers the temperature of a greenhouse. Adjusting the degree of the coupling to each by adjusting the optical properties of the glazing allows one to adjust the temperature of the greenhouse above or below that of the surrounding environment. — Cortonin | Talk 16:05, 29 Mar 2005 (UTC)

thermal frequencies?

Vsmith, there's no such thing as a "thermal frequency" in the context of "thermal and IR frequency". I'm not sure what you're talking about. The term "thermal IR radiation" refers to a particular subset wavelength range of infrared radiation. — Cortonin | Talk 02:29, 29 Mar 2005 (UTC)

Hmm... probably correct there, however, I think that bit came from one of your references which broke IR into near IR and Thermal IR. Seems like it may have been the PDF file, would have to go back & check. IR is a rather wide freq range and different glazings are more absorbent in different parts of the IR spectrum.

I changed that a bit when I reverted your unlabelled two part complex revert :-) Vsmith 03:18, 29 Mar 2005 (UTC)

The range of concern for the absorption of Earth-temperature blackbody radiation is thermal IR. Near IR is of concern because a significant, but lesser, part of the incident solar radiation is in the near IR band. — Cortonin | Talk 04:51, 29 Mar 2005 (UTC)

Points of contention

Document the following points with detailed mechanistic descriptions from the literature, or stop reverting to them, because they contradict documentation already present in the article:

• The actual maintaining of higher temperatures inside of a greenhouse is due most importantly to the inability of the natural convective flow to carry away the excess heat. and Unlike a real greenhouse where the blocking of convection is a dominant heat maintaining factor

• Contradicted by the Horticern paper which shows temperature difference does not change significantly as rate of convection increases, and sometimes reduces. — Cortonin | Talk 05:17, 29 Mar 2005 (UTC)

• In the global greenhouse effect the major thermal control is the infrared absorbent effect of the greenhouse gases.

• Contradicted by the numbers RIGHT BENEATH it, which show that global atmospheric convection reduces the temperature from 72C to 15C, meaning that atmospheric convection eliminates over half of the warming effect of the greenhouse effect. It would not be appropriate to call infrared absorption the major thermal control here when a larger portion of the temperature difference is attributed to atmospheric convection. — Cortonin | Talk 05:17, 29 Mar 2005 (UTC)

• outgoing thermal and IR frequencies

• It is not correct to say "thermal frequences". First, when discussing spectra effects, these are typically described in terms of wavelengths. Second, there are "IR wavelengths", of which "thermal IR wavelengths" are a subset. Separating them like this makes no logical sense. The term "thermal frequency" has meaning which is well outside of the scope of this article, and for this topic, is simply a non-existent term. — Cortonin | Talk 05:17, 29 Mar 2005 (UTC)

• in which they lay additional plastic sheeting inside a greenhouse in order to retain additional warmth to plants or water pipes in the enclosed area by further reducing convection within a local part of the greenhouse.

• Plastic sheeting DOES NOT WORK BY CONVECTION SUPPRESSION. This is contradicted by the Horticern paper's description of the greenhouse effect, and by the very description of the plastic sheeting products themselves, as seen here. — Cortonin | Talk 05:17, 29 Mar 2005 (UTC)

All of the above excerpts are wrong. There is a reason I am reverting them, and this is because they are incorrect and violate basic thermodynamics and all of the available literature. No one here has come forward with any detailed prominent documentation which supports those statements, but detailed prominent documentation has been put forward showing that they are incorrect. The personal interpretations of Wikipedia editors as to how they think a greenhouse might operate do not override the publicly accepted mechanisms as documented in the literature. If you want to put any of those statements back, FIRST go do a literature search and find a detailed mechanistic description of the greenhouse effect which supports that particular statement, and THEN restore it with that new documentation. — Cortonin | Talk 05:17, 29 Mar 2005 (UTC)

(William M. Connolley 11:23, 29 Mar 2005 (UTC)) I have provided numerous quotes from the meterological literature demonstrating that GH's work primarily by preventing convection. You ignore all that with spurious excuses and conduct you own original research instead. Shouting at us will not help you. You provide http://www.greenhouses-etc.net/glazing/polyfilm.htm, which (of course) you have misunderstood: we all accept that trapping IR can have some role to play, which is all that the page demonstrates: your point that it is the *major* contributor is quite wrong. You have the gall to say The personal interpretations of Wikipedia editors as to how they think a greenhouse might operate do not override the publicly accepted mechanisms as documented in the literature.. Unfortunately that is exactly what you are doing: substituting your own pers res over what the meteorological litereature clearly states.

I will repeat: Find a detailed mechanistic description of the greenhouse which supports the above particular statements. You have not. "It's a misnomer" is not a detailed mechanistic description, and tells you nothing about the function of a greenhouse. Those statements remain undocumented. If you're going to try to argue from the position of science, then try to argue with scientific descriptions rather than fiat! Find a description in the literature which describes that "model" of operation for any of those four statements. — Cortonin | Talk 14:49, 29 Mar 2005 (UTC)

Sue Ann Bowling webpage

Vsmith added this reference. I'll note firstly that this is not a publication in the literature, so it still does not address the lack of documentation for the above points of contention. But secondly, it contains errors. It begins with the premise that polyethylene greenhouse covers are transparent to IR, which is incorrect. Some are available with lower IR absorption because they contain no coating or embedded absorption material, as can be seen in the table of R values here (note the polyethylene single film's low value on this table), and those would result in much more significant heat loss, by up to a factor of 3. But glazings are purchased for their IR absorption properties, as seen here. Greenhouses which do not use appropriate glazings for their surfaces require supplemental heating to maintain their temperatures, because they cannot do it by virtue of the greenhouse effect, and this is not part of the material that has been described in this article so far. The Bowling webpage correctly asserts that thermal IR absorption in the glazing is the primary factor which keeps a greenhouse from losing heat at night, but it fails to correctly extend this to daytime consideration, when the greenhouse is losing heat energy to the sky at essentially the same rate, but is simply obtaining more incoming energy from the sun than it is losing. This is why it's good to stick with peer reviewed material when trying to discern how a greenhouse actually operates. They actually test what they write down. — Cortonin | Talk 19:41, 29 Mar 2005 (UTC)

Atmospheric Convection

Vsmith, your sentence misrepresents the statement from this reference. The reference states, The Earth, in contrast, loses no heat by convection, but only by radiation. Convection in the oceans and atmosphere merely serves to redistribute the heat., which is true. However, you cannot translate this into saying that the greenhouse effect is "the major thermal control". Convection does not result in a direct loss of heat in the atmosphere, but it does facilitate a rearrangement of heat energy which has an enormous impact on the resultant temperature of the planet. This effect is so large that it cancels out over half of the greenhouse effect. There is no reason to say then that IR absorption is the major global thermal control. What you should be saying is that it is an IMPORTANT thermal control, if you want to say anything about it. "The major" is an evaluative judgment which is not supported by the numbers. — Cortonin | Talk 09:05, 31 Mar 2005 (UTC)

How about the greenhouse gases are the most dominant block for heat loss from the atmosphere. Convection simply redistributes the heated air - making it more uniform and cooler at the surface.

GH gases keep it in - convection spreads it around. Gotta keep it in to have any to spread around. Vsmith 17:02, 31 Mar 2005 (UTC)

I don't think you need to throw in the phrase "most dominant", but otherwise yes. Greenhouse gases are a significant block to radiative cooling, and it results in a significant rise in global temperature over the freezing state it would otherwise be. And atmospheric convection makes a large reduction in the effect of greenhouse gases, removing over half of the effect. — Cortonin | Talk 18:13, 31 Mar 2005 (UTC)

Why you keep insisting on reverting the logic of "mechanism" is beyond me. It's as if you're only considering things which cause heating to be mechanisms, rather than things which do an action. This results in you ignoring the very active contribution of convection to the temperature of the atmosphere, and considering thermodynamic isolation to be a mechanism. I don't have the least bit of a problem with calling thermodynamic isolation thermodynamic isolation. The only thing I have a problem with is when you start saying the greenhouse works by being isolated, or the mechanism of operation is isolation, or the dominant mechanism is isolation from its environment. This violates both the meaning of mechanism as an active thing, and it violates the experimental numbers which show convection to be a minor thing when comparing the temperature difference between the inside and outside of the greenhouse. It's incorrect at both levels of consideration to phrase it that way. — Cortonin | Talk 09:05, 31 Mar 2005 (UTC)

Mechanism...hmm... If you don't have: 1. a means to get the sunlight in, and 2. a way to keep the heated air from convecting away, you don't have a greenhouse. Thes are prerequisite for any research on glazings or whatever. A greenhouse won't function without BOTH, therefore they are of prime importance in discussing any real greenhouse effect or mechanism. Vsmith 17:02, 31 Mar 2005 (UTC)

This is why the article describes the greenhouse as a thermodynamically isolated system. I think we have that covered. — Cortonin | Talk 18:13, 31 Mar 2005 (UTC)

For example, of two statements that you have just added, saying "The research starts with the blocking of convective heat loss as a given in an isolated system" is thermodynamically valid. Saying "in order to provide additional warmth to plants or water pipes within the enclosed area by further reducing convection" is complete nonsense. If you want to describe thermodynamic isolation, you have to describe it in the first way, because the second one is not what actually happens. — Cortonin | Talk 09:05, 31 Mar 2005 (UTC)

Nonesense hmm... Limit the convection to the lowest 1/4 of the GH volume (down where the warm ground is) and the restricted area stays warmer because the air is not convecting with the cooler upper parts of the GH. Same amount of heat confined to a smaller area should mean it'll stay warmer longer. Vsmith 17:02, 31 Mar 2005 (UTC)

Not meaningfully. An infinitismal amount, yes, but you have to consider the relative heat capacities of the ground and the air. The specific heat capacities of soil and air are roughly the same, but the density of soil is roughly 2000 times higher than the density of air. This means that the heat capacity of a clump of soil is 2000 times more than a corresponding volume of air above it. In other words, the amount of air enclosed makes an almost infinitismal contribution to the temperature of the system when considering redistribution of energy. Now if you were to enclose different depths of water buckets within plastic shielding, then you'd have something. In this case, the temperature difference between that and the environment would be roughly inversely proportional to volume. But when you're considering enclosed air, then this effect is approximately zero. — Cortonin | Talk 18:13, 31 Mar 2005 (UTC)

The greenhouse loses almost no energy directly by convection, and similarly, the atmosphere loses almost no energy directly by convection, so there is no point in considering a difference between these two. The only difference between the two systems is that the atmosphere can have significant convection around the greenhouse barrier, while the greenhouse doesn't have significant convection around the greenhouse barrier, and the atmospheric energy can then radiate without being absorbed by the greenhouse effect. It baffles me that I have a bunch of environmentalists here taking this atmospheric redistribution and then trying to argue that the greenhouse effect is weak in the greenhouse. I have news for you, if the greenhouse effect were weak in the greenhouse, it would be much much weaker in the atmosphere. This was the one thing Wood 1909 got right. And if he were correct, then we would have almost no atmospheric greenhouse effect (because with convection redistributing energy beyond the greenhouse barrier, the atmospheric greenhouse effect can only be weaker than the gardening one), and as a consequence, there would by default be no possibility of significant global warming given any concentration at all of greenhouse gases. What a number of you have failed to realize is that by this anti-physics argument about how a greenhouse operates, you're effectively declaring that there is no possibility of any significant global warming. Declaring no possibility of significant global warming is a far more extremist position than I would take, and I have no idea why it's being supported here by people who are also strong supporters of a large GHG global warming effect. — Cortonin | Talk 09:05, 31 Mar 2005 (UTC)

But, the greenhouse would loose gobs of heat by convection if not for the blocking of convection by the enclosure. We're not talking about convecting beyond the atmosphere (or whatever you are saying) - and am not sure at all of the point of the rest of this. Seems to be off in left field somewhere - I see no relevance. Anti-physics arguement?? Again, with no enclosure to control convection and no way to get sunlight in, all the super glazing researchers and salesmen in the world won't a greenhouse make. Vsmith 17:02, 31 Mar 2005 (UTC)

This is the structure of a greenhouse, not its mechanism of operation. And this is why the structure is described as a thermodynamically isolated system. — Cortonin | Talk 18:13, 31 Mar 2005 (UTC)

Let me try to simplify the above: If you think greenhouses with IR absorbent surfaces don't experience a large amount of heating due simply to thermal IR absorption, then why would the atmosphere experience heating due to this? — Cortonin | Talk 18:13, 31 Mar 2005 (UTC)

(William M. Connolley 20:10, 31 Mar 2005 (UTC)) Because, weirdly enough, GH's and the atmos are different: one is much bigger is the most obvious start. Wiki is not here for discussions of physics: its here to summarise and report existing research. Which you continue to reject, sadly.

Yeah, so it's bigger. And once again, why would the atmosphere experience heating due to thermal IR absorption if it didn't happen in a greenhouse? — Cortonin | Talk 03:07, 1 Apr 2005 (UTC)

Different design maybe :-) IR absorption does occur in both - just the different scale and proportion of it's contributing role is interpreted differently by different folks. Just like some here seem to think that blocking of convection between the greenhouse environment and the outside environment is just a minor detail, "an isolation of the system", rather than a major or even dominant reason that greenhouses work. If you isolate out an important variable and say it doesn't have any importance on an experiment, then maybe your experiment is incomplete and the results questionable. Vsmith 12:05, 1 Apr 2005 (UTC)

What different design? Thermal IR is absorbed. In the one with variables reducing the effect, you believe it makes a large temperature difference, and in the one with very little reduction of the effect, you believe it makes no, to almost no, temperature difference. Does this really make sense to you? — Cortonin | Talk 19:18, 1 Apr 2005 (UTC)

If you want existing research, read the Horticern paper. I have not rejected it. — Cortonin | Talk 03:07, 1 Apr 2005 (UTC)

Obviously different published papers are saying different things, different foci, different resulti. Research focussing on greenhouse glazing seems to isolate out any convection concerns. If you want to make and sell high tech glazings, you focus only on what the product will accomplish. If you place a horizontal piece of high tech glazing over your tomato plants and leave the sides open, how effective is this open to convection greenhouse?

It's called an "open greenhouse", and yes, it still works, and it still produces heating effects. If you look here, an arctic open greenhouse is quoted as 2.8C heating, versus 3.9C for the closed greenhouse. (Unsurprisingly, convection reduces thermodynamic isolation, and reduces heating effects obtained in other ways by temperature exchange with the ambient temperature.) That most of the heating is still obtained should not be too surprising, after all, if you stand in the shade such that you're blocked from the sun, then you still feel cooler even though convection is present and allowing interchange with the unshaded areas. Thermal IR absorption can essentially be thought of as "shading" from the cold temperatures of the sky. — Cortonin | Talk 19:18, 1 Apr 2005 (UTC)

Hmm... the ref. states "Both types ... had an open top of 40 x 40 cm in the middle." And were "50 cm high, with 1.2 x 1.2 m surface area". So neither was convection isolated and therefore sorta irrelevant to the current discussion. No one is saying that there is no IR absorption effect. Vsmith 17:30, 3 Apr 2005 (UTC)

I'd read the fabulous Horticern paper if I could, but just don't give it priority enough to put out the effort now - don't have ready access to a univ. library that might have it. Who sponsered it and did they isolate out any consideration of convection? Vsmith 12:05, 1 Apr 2005 (UTC)

Well, if you don't read the scientific literature, then it's hard to make arguments about what it states. It was done by researchers at CERN, and they included convection in their model and directly experimentally measured the effects and contributions of convection. This is why I've been telling you (and WMC) to read it, although it would appear neither one of you has. — Cortonin | Talk 19:18, 1 Apr 2005 (UTC)

Thanks for the patronizing attitude - and being as you have sorta mis-represented other refs in the past (we all do - based on our background baggage or bias), and although CERN is a respectable outfit without knowing their bias I remain a bit skeptical. Just how did they include convection? :-) Vsmith 17:30, 3 Apr 2005 (UTC)

Since you asked I will attempt to describe it to you, and I will ask you to either accept that I am correctly summarizing the relevant areas as you asked, or go read it to see for yourself. The description focuses on the specific thermal loss coefficient, U, which is a function of windspeed and the apparent sky temperature (thus, explicitely including the two experimental quantities which describe rates of convective and radiative energy loss). The apparent sky temperature is determined by measuring the incident thermal radiation from all over the sky (note that this is the thermal radiation from the sky, not solar radiation from the sun), and using the Stefan-Boltzmann equation to calculate an apparent radiative temperature from this. I will quote from the article, "Greenhouse thermal losses are the sum of three thermal exchanges: between cladding (its outer surface) and outside air, between cladding and sky and between inside and outside air by air infiltration or by conduction in the ground." These are expressed in terms of transfer coefficients times the temperature difference between each region, and through simple algebra, this is reduced into an equation relating inside air, outside air, and sky, with a parameter q_sky, which is a measure of sky temperature influence. q_sky = (T_out - T_sky)/(T_in - T_out). A discussion then ensues about the meaning of q_sky, where in particular it is noted that q_sky is largest when the inside and outside temperatures are closest to equal. This is particularly relevant to our discussion, since it shows that the sky temperature influence is overwhelmingly dominant when the inside and outside temperatures are equal (such as when the system "begins"), and the relative influence of the sky temperature only levels off when the difference in temperatures between inside and outside becomes large so that it is comparable to the difference between the outside temperature and the sky temperature. This can perhaps give you a numerical feel for how the blocking of coupling to the sky temperature acts as a temperature rising agent (since the outside temperature is being continually lowered by this coupling), and then convection and conduction act as a force to bring the inside temperature into equilibrium with the outside temperature, and this equalization force only becomes significant when the temperature is raised by other means, namely, the blocking of thermal IR coupling to the sky. Within the paper, this model is experimentally confirmed to have predictive accuracy within about 10% for a wide variety of greenhouse configurations. A good portion of the paper describes calculation of powered heating requirements for greenhouses with insufficient insulation, glazing, and heat storage for their environment. These last parts would perhaps make interesting additions to this article, if we could get past the basic premise of how a greenhouse operates, as described at the start of the paper. — Cortonin | Talk 18:16, 6 Apr 2005 (UTC)

(William M. Connolley 22:27, 6 Apr 2005 (UTC)) I have the Horticern paper. I've read it. Its not terribly relevant or indeed terribly useful for the purposes of these pages. In particular it doesn't specifically address the question of the relative amounts of energy lost through radiation or suppression-of-convection (which is why C is reduced to rather vague stuff above about "this can perhaps give you a numerical feel" - because in fact numbers are lacking) . C quotes: 'Greenhouse thermal losses are the sum of three thermal exchanges: between cladding (its outer surface) and outside air, between cladding and sky and between inside and outside air by air infiltration or by conduction in the ground indeed. Now lets read that *literally*: there is no mention of radiative losses at all from the inside. How can this be? Because the cladding is assumed IR opaque? This is never mentioned and is not a good asssumption for all materials. The paper simply does not address the issues which we are disputing at all.

I appreciate that you got the paper, that will assist discussion of it. However, if you are looking at it for some sort of number expressing a "relative amount of energy lost through radiation or suppresion-of-convection", then you are looking for something which doesn't exist. First, the correct thing to look for, if you wish to consider it, is the relative amount of energy lost through radiation and through convection. No energy is lost through suppression of convection, since suppression means nothing is happening. And the factor describing the relative factor of radiative loss to the system is q_sky, as described in the paper. If you're looking for a specific number, this would not be sensible because as I described above, the influence of the sky temperature dominates while the greenhouse is heating up from equal to the outside temperature, but as the greenhouse gets hotter and the temperature levels off at its stable hot temperature, then more of the energy is lost through convection and conduction, since T_in - T_out is growing. — Cortonin | Talk 18:59, 7 Apr 2005 (UTC)

In addition, the cladding is not at all assumed IR opaque in the paper. If you read it carefully, you will see that they explicitely examine a wide variety of glazings with different thermal IR properties, and they experimentally compare the success of their model under this range of glazings, and find it to be accurate. If you look at the diagram on page 9, right beneath the description I quoted, you will see clearly that the inside air is coupled to the cladding by an exchange term which takes into account the absorbence of the glazing. The sentence says "greenhouse thermal losses..." because it's including the loss from the greenhouse to the environment, through which the radiative loss does occur at the outer surface of the glazing if you draw that as the reasonable boundary of the greenhouse. — Cortonin | Talk 18:59, 7 Apr 2005 (UTC)

A large problem with using this paper is that it is focussed on the need to maintain the internal temperature, thus the critical variable they want is the energy need, E_need. Thus the situation is different to a passively solar heated GH.

The model is equivalent, you simply don't include the heating. For greenhouse designers, the heating is often important, since many greenhouses are not designed well enough to heat themselves optimally. — Cortonin | Talk 18:59, 7 Apr 2005 (UTC)

I don't think C has understood the sky temperature thing at all. The sky temperature matters because it gives you downward longwave. But this tells you nothing whatever about the partition of heat losses between upward longwave suppression, and convection suppression. Something that does, though, is Spencer Wearts nice "discovery of global warming" site, which says This was an over simple explanation, for it is quite different physics that keeps heat inside an actual glass box, or similarly in a greenhouse. (The main effect of the glass is to keep the air, heated by contact with sun-warmed surfaces, from wafting away.) [15].

The Spencer Wearts site is simply rehashing the same Wood 1909 paper, as this is the only reference he quotes to support his statement (although he does quote a couple references which disagree with his statement). The Wood 1909 paper is not even a properly controlled experiment, and does not compare to modern thorough examinations. — Cortonin | Talk 19:16, 7 Apr 2005 (UTC)

Yes, the sky temperature tells you downward longwave, and downward longwave is the critical value which tells you the radiative loss the OUTSIDE experiences.

(William M. Connolley 09:27, 11 Apr 2005 (UTC)) No, downward longwave tells you how much LW is going down. It doesn't tell you how much is going up, which depends on the sfc t of whatever is the sfc.

??? The energy going up is found from the amount going up minus the amount going down, and is thus a function of surface temperature and sky temperature. I'd love to see you write down an equation which tells the total energy going up without using the amount of LW going down (or its equivalent metric, sky temperature). — Cortonin | Talk 16:52, 11 Apr 2005 (UTC)

It's the active elements which are important in thermodynamics, not the inactive elements. The outside environment is actively coupled to the sky, so the rate at which it is losing energy is determined by the difference of the temperature of the outside and the temperature of the sky as determined by downward longwave. It's a symmetry thing, thermal IR is coming down and going up, and if more goes up than goes down (because the ground is hotter), then the ground cools off until the two balance out. The coupling rate between these two is reduced by the absorbence in between them. The greenhouse glazing absorbs both the downward thermal IR and the updward thermal IR, and the net result is that the coupling rate is reduced and the rate of loss is significantly slower than the rapid rate the outside experiences. So as the paper says, q_sky does precisely tell you the influence of the sky temperature, which is precisely the influence of radiative loss. — Cortonin | Talk 18:59, 7 Apr 2005 (UTC)

IR Calculations and Sky Temperature

There are some calculations out there on the internet which attempt to calculate the rate of energy loss due to IR exchange with the sky. Unfortunately, some of them either make the mistake of assuming the IR exchange occurs with the ambient environment, or the equivalent mistake of assuming the sky temperature is equal to the ambient temperature. However, all the peer reviewed papers which point an IR thermometer up at the sky agree that the radiative sky temperature varies between about 6-26 degrees celsius below the ambient temperature (depending on cloud cover), with an average somewhere around 15 or 16 degrees celsius below the ambient temperature. This is the cooling force which cools the outside environment, but which doesn't cool the inside of the greenhouse, because the inside of the greenhouse is isolated from that strong cooling influence. Any calculation which attempts to IR balance between the greenhouse and its surroundings will yield a significantly incorrect result, since the actual physical system IR balances with the much cooler upper sky. I just leave this as a notice for future editors to be aware of. — Cortonin | Talk 19:01, 13 Apr 2005 (UTC)

Temporary injunction

Copied here from Wikipedia:Requests for arbitration/William M. Connolley and Cortonin#Temporary injunction:

Since revert wars between the Cortonin and William M. Connolley have continued through this arbitration, both users are hereby barred from reverting any article related to climate change more than once per 24 hour period. Each and every revert (partial or full) needs to be backed up on the relevant talk page with reliable sources (such as peer reviewed journals/works, where appropriate). Administrators can regard failure to abide by this ruling as a violation of the WP:3RR and act accordingly. Recent reverts by Cortonin [16] [17] [18] [19] [20] by William M. Connolley [21] [22] [23] [24] [25] Additional reverts by others involved in these revert wars may result in them joining this case.

--mav 22:44, 23 May 2005 (UTC)