Talk:Greenhouse effect/Archive 2

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Convection

The claim that the greenhouse effect works by blocking convection is absurd. That's like saying a tea kettle works by blocking drainage. It says nothing about what drives the temperature up. (With your windows and doors closed, your home also acts as a barrier to convection, but that doesn't make it a greenhouse.) Consequently, the claim on this page that the term "greenhouse effect" is a misnomer is also incorrect. The description there of how a greenhouse works makes no mention of how the glass blocks the transmission of infrared radiation. This is confusing and misleading. I first encountered these claims on a web site funded by the oil industry that professed to "explain" the greenhouse effect but only clouded the issue (If you'll excuse the expression). (I first raised this point in the Solar greenhouse (technical) discussion, but this seems to be a better place for it.) --MiguelMunoz 18:38, 28 July 2006 (UTC)

I am sorry Miguel, but you are mistaken. The greenhouse effect describes processes by which the heat generated by solar radiation is trapped near the surface of the Earth. For the Earth as a whole, this is accomplished primarily (but not exclusively) by the absorption of infrared radiation by greenhouse gases in the atmosphere. However, for the greenhouses that we build, heat is trapped near the surface primarily (but not exclusively) by the enclosed space which prevents the warmed air from rising to mix with other, cooler portions of the atmosphere. People can build a perfectly functioning greenhouses with materials that are totally transparent to infrared. Talk:Greenhouse effect/Archive 1 and Talk:Solar greenhouse (technical)/Archive 1 have some very long (and argumentative) discussions of this. Dragons flight 19:10, 28 July 2006 (UTC)

On People can build a perfectly functioning greenhouses with materials that are totally transparent to infrared, see http://www.wmconnolley.org.uk/sci/wood_rw.1909.html William M. Connolley 20:21, 28 July 2006 (UTC)

Miguel - I don't understand either of the points you are trying to make.

"The claim that the greenhouse effect works by blocking convection is absurd.". The article is very clear that the greenhouse effect works by the absorption of infra red radiation. It is only the glass structure used in gardening (a glasshouse to give it an old fashioned name) that works by blocking radiation. This is mentioned towards the end of the article after an extensive discussion of radiative transfer.

Secondly I can't see why you claim "It says nothing about what drives the temperature up" when the second sentence of the Real Greenhouses section states "it heats up primarily because the Sun warms the ground inside it". If this was not mentioned your analogy with a home would be valid - however the source of the heat is mentioned as well as the mechanism by which the heat is inhibited from escaping.

I would however add that I think it is a mistake to mention glasshouses in the lead section and some mention of IR there might be useful.--NHSavage 20:57, 29 July 2006 (UTC)

Okay, I also take issue with the claim that the greenhouse effect is so named because of an incorrect analogy with the functioning of a greenhouse. While it may be true that functioning greenhouses can be built without materials that trap re-radiation of infrared, it is nevertheless the case that a significant portion of greenhouses use more standard IR-blocking materials, and that a significant portion of their heat comes from that process. In fact, the article about greenhouses on this very site explains the heating mechanism in terms of trapping re-radiated IR, so to call the analogy false creates a lot of confusion. Perhaps a better statements would be "the greenhouse effect's name come from an analogy to one of the mechanisms that heats up real greenhouses". This sentence doesn't mislead people about the functioning of greenhouses, or about the connection between them and the greenhouse effect.

it is nevertheless the case that a significant portion of greenhouses use more standard IR-blocking materials, and that a significant portion of their heat comes from that process. - who says that a significant portion of their heat comes from that process - you? I'm afraid you;ll need rather better than an unsupported assertion, no matter how "obvious" is may be to you. Solar greenhouse (technical) does *not* say that IR trapping is a major effect - it says, just like this page, that first is the stopping convection and only second is IR William M. Connolley 19:39, 17 November 2006 (UTC)

Cleanup

This article seriously needs cleanup. --scienceman 17:04, 25 July 2006 (UTC)

WH nonsense

I deleted http://www.warwickhughes.com/icecore/. Not only is it rubbish, its also misleading: despite purporting to be a statement given in evidence, it wasn't William M. Connolley 15:52, 28 September 2006 (UTC)

"Real greenhouses"

As far as I can see the section "Real greenhouses" is misleading, incorrect and should be removed. In order for something to be warmer than its surroundings there has to be some phenomenon that makes it warmer. That phenomenon is (roughly speaking) that it lets sunlight through, but not the blackbody radiation from the earth. In order to keep it warmer than its surroundings you have to restrict the transport processes that otherwise will cool it until it reaches the temperature of the surroundings (in this case the glass structure that keeps it from mixing with the surrounding air). That is however not the primary reason for the warmer climate within a greenhouse, it is just a condition. If you leave a house (or any other closed volume with the about the same properties as the surroundings) unheated for a reasonably long period the temperature within the house will not differ from its surroundings.

One of the two links given do actually deal with finding errors in Mr Wood's argument (no. 7 at the moment), while the other one is a rather political page of low quality. Gunnar Larsson 18:32, 16 October 2006 (UTC)

First of all, this has been extensively discussed. Its one of the few points of fact that have an arbcomm ruling in their favour. But we can still talk about it... AFAIK "bad greenhouse" doesn't point to any errors in Wood; be so kind as to quote the piece you have in mind. If the other "low quality" page is mine I fear I disagree with you; I point out the only flaw I know of in Woods paper.

But on to your: That phenomenon is (roughly speaking) that it lets sunlight through, but not the blackbody radiation from the earth. This is simply a bald and unsupported assertion. From a theoretical point of view its a possibility; however, observational evidence is against it. You are correct in your restrict the transport processes that otherwise will cool it - and the transport process that is restricted is movement of heat by movement of air: direct thermal advection. I don't understand your house bit: if you mean, a closed volume with few openings for light, then yes of course: because there is no internal heating from sunlight William M. Connolley 19:15, 16 October 2006 (UTC)

Real greenhouses 1

I don´t know whether the Wikipedia´s section "Real greenhouses" was written based on IPCC background or is independent, however, in both cases almost all of the section´s concepts are completely wrong, as demonstrated below:

1st. The greenhouse effect is NOT a misnomer! Both the atmospheric greenhouse effect and real greenhouses have very very similar behaviours.

2nd. The real greenhouses do NOT suppress convection!

3rd. The comparison of the atmospheric greenhouse effect with that from a real agricultural or for home heating greenhouse is CORRECT, but not complete. The more complete or more correct comparison should be made with another type of greenhouse called "solar still", where there is also a water surface and evaporation.

4th. In fact, a greenhouse, in comparison with an equivalent open system REDUCES the convection, but NOT only the convection! Besides the convection, also the radiation and evaporation emissions from bottom to top of the system decrease. Contrary to these three modes, the conduction heat transfer from bottom through the soil increases, due to the higher soil or water temperatures attained in greenhouse systems. These explanations are clearly shown in Sartori (1996)*, whose paper seems to be the only one in the world that compares scientifically the behaviour of an open solar evaporation system with a closed one (solar still), where the greenhouse effect takes place. With some identifiable differences, the behaviours of such systems are very similar to those of the atmosphere when it is more open and when it is more closed.

Sartori, E. Solar still versus solar evaporator: a comparative study between their thermal behaviours. Solar Energy, 56/2, 199-206, (1996).

5th. The real greenhouse does NOT suppress the turbulent mixing! The IPCC or Wikipedia demonstrate not having the proper basic scientific background to know that from an open to a closed system (greenhouse) the convection is NOT suppressed, but only converted from FORCED to FREE convection while the turbulent flow CONTINUES working! I work theoretically and experimentally with such systems and there are scientific works that show this clearly, including experimental ones that show this through flow visualizations where the turbulent mixing is clearly observed.

6th. In the atmosphere, the Sun ALSO heats up the soil or water surfaces, which warms up the air in contact with them through convection. And when the sky is completely cloudy, this air is prevented from flowing away directly beyond the cloud cover. Directly means NOT changing the original convection process, because within the clouds happen different convection processes from the one that brings up the air from ground to the cloud cover. Thus, when the sky is more open, there is a small greenhouse effect, but when there is a strong cloud cover the greenhouse effect is much higher (with the constant amount of CO2, CH4 and other gases), as shown in Sartori (1996) and in http://noparadoxes.tripod.com.

7th. The ingenuous scientific background of the Wikipedia´s section "real greenhouses" is tremendous! Opening a window of a greenhouse does NOT correspond to a proof of the convection suppression! ON THE CONTRARY, when you open such a window the free convection inside the greenhouse is replaced by the forced convection, which withdraws more heat from indoors than before when the window was closed. Because more heat flows to outdoors, then the inner temperature decreases, and this process corresponds and is a consequence of the Second Law of Thermodynamics.

8th. Even in agricultural greenhouses where there isn´t free water surfaces the convection is NOT suppressed! Whenever and wherever there is a temperature difference there is convection! Thus, almost never you will have a suppression of convection naturally. This is a tremendous elemental concept of the heat transfer area that I don´t believe that such Wikipedia section was written by specialists. Worst if such elemental erroneous concepts are adopted by the IPCC.

9th. Almost all of the concepts of the Wikipedia´s section "Real greenhouses" are completely erroneous and incomplete and do not contribute to the advance of the understanding of the greenhouse effect, and must be withdrawn from the page in order to really give a contribution to the true science.

10th. In the article http://noparadoxes.tripod.com the author demonstrates lots and lots of errors contained in the essential concepts utilized by climatologists since more than a century ago, errors very similar to those contained in the section "Real greenhouses". Thus, it will not be a surprise if someday we know that the concepts shown in the Wikipedia´s section "Real greenhouses" are also adopted or were inspired by the IPCC, which is formed essentially by climatologists. —Preceding unsigned comment added by 201.86.243.200 (talk) 22:48, 2 December 2007 (UTC)

The relative roles of convection, conduction, evaporation and emission for GH temps

I know this is a sore point on this discussion, but there is a relatively simple experiment that illustrates the importance of emission and selective surfaces for the heating of greenhouses. Take two pieces of blued steel (coated in a fine layer of black iron oxide) and paint one with black paint. Leave both out in the sun with no covering. Carefully touch both with your finger.

The unpainted iron will probably burn your fingers, the painted one will be just warm.

Why is it so? The black iron is a good selective surface, having very little absorbtion (and thus emittance) of thermal IR. Black paint, on the other hand, is close to a black body (usually consisting of carbon black) and radiates lots when it gets hot.

Thus, for collecting heat you want to stop the emission of IR but allow the absorbtion of PAR.

This is not the full story, however. Plants themselves do not thrive when the ground is warm and the leaves are cold, as most of the chemical action takes place in the leaves. Thus, we wish to transfer heat collected from the sun to the air around the leaves. We might try to do this by putting a large selective surface under the plants, but in practice although the collector would get hot, much of the heat would be lost to surrounding air by convection. Thus, we trap the air in a box (and for other reasons too).

Another important source (currently not mentioned in the article) of heat loss in greenhouses is evaporation. Losing half a gram of water a second as vapour is more heat loss than the maximum heating effect on a square metre of direct sunlight. Controlling this is thus very important. Plants naturally try to evaporate water as part of their living process.

Finally, we have conduction. Glazings generally are very poor insulators, being so very thin. More significant is the boundary layer of air, but inside a greenhouse we lose half of this to condensation (as water vapour happily crosses the boundary layer by diffusion). Thus double wall films are quite effective.

So, it is true that IR emission is very important for efficient collection of light energy, and important for reducing losses at night, but convection and water vapour transfer is far more effective at cooling a greenhouse. My double walled, TIR blocking greenhouse is cool in summer simply by opening a 1m² hole in each end and relying on the cooling effect of evaporation, driven by convection. Thus, controlling air movement is the first priority of greenhouse design. Once you have sealed everything up, then you look at TIR for further thermal storage.

We might ask what the best use of a dollar for improving greenhouse heating costs is. Experience is that we should, in order, a) remove all air leaks, b) use IR blocking films, c) reduce conduction with extra layers. Thus, the options on commercial greenhouses are usually a) cheap UV only film, b) UV and IR film, c) double layer designs. Because of the massive effect of air transfer, this is assumed to be controlled first. My greenhouse rep tells me that until the relatively recent development of good IR PE films, polyethylene films with only UV block were the most commonly used. Recent advances in IR coatings have made these now commercially viable for growers.

Finally, there are 90% PAR transmitting woven cloths that block both UV(for longer life and human protection) and TIR(due to the kind of plastic) but allow significant air movement. These are commonly used in Australia for growing certain kinds of Orchid. Although 90% of the energy of the sun is reaching the ground, the large air transfer means that these environments only heat very slightly above ambient, and cool very quickly at night. Their multi-layer woven design means they should be quite good at blocking TIR(there are no visible holes through).

Regarding the real greenhouse effect, clearly convection, conduction and latent heat do not cross space, but do have an effect on global temperatures by moving heat from ground level where the light is absorbed to the upper surface where there is less insulating TIR blocking gas. I do not know anything about the importance and magnitude of that and will leave discussion to experts. -- njh 09:56, 18 October 2006 (UTC)

Right now, it is semi-protected, so IP users may register and do something so disruptive that it may get heavier than it sounds. Even with "calmer" edits, we can't unprotect it without entering a request in wikipedia:requests for page protection nor can we remove the tag until a season or so. Agree? --Gh87 06:39, 28 October 2006 (UTC)

Anon Q

An anon asks (but did it by rubbing out another anon Q, so I've (William M. Connolley 16:34, 9 November 2006 (UTC)) re-added it here):

what about the greenhouse effect, not always associated with the earth's atmosphere?

what about the greenhouse effect which is linked to heat transfer?

--Jan Lindstrom ----

According to the IR-transmission spectrum, CO2 is an effective absorber. Parts of the window indicate 100% absorption (is this really true?). If so, what is all the CO2 fuzz about? Surely an increase in CO2 will not have any influence on climate, i.e. the spectrum window is already "saturated". Please, correct me on this or else I´ll turn into a skeptic.

You seem to have answered your own question. Only parts are saturated William M. Connolley 12:16, 21 November 2006 (UTC)

"Skeptics" try to argue it both ways. First, that there is not enough CO2 to absorb enough IR to affect the climate. Secondly, that the CO2 is saturated. In fact, the rest of the atmosphere acts as a sink for the CO2 to "desaturate" it; IR is absorbed by the CO2, the heat is transferred to the nitrogen/oxygen; repeat. This is not something that the IPCC stupidly overlooked. Gzuckier 15:53, 21 November 2006 (UTC)

runaway again

The current section on runaway greenhouse is badly confused and confusing. Its not even clear in what sense the term is being used. Or even if it has an accepted definition. Its clear the Earth has never had a runaway GHE or we wouldn't be here. If the Permian stuff was caused by GHE - and that isn't at all clear - it was merely positive feedbacks leading to an large increase - this is something entirely different. I think the section should be drastically trimmed William M. Connolley 23:26, 22 November 2006 (UTC)

Positive feedbacks can't last forever. No article wich use the term "runaway" said that they could.

The term "runaway greenhouse effect" is present in 347 articles according to scholar.google

http://scholar.google.com/scholar?q=%22runaway+greenhouse+effect%22&hl=en&lr=&ie=ISO-8859-1&btnG=Search

We can obvisouly see that the term "runaway" is only employed when there is a large positive feedback (when the series diverge until no more A gas can be supplied).

I propose a new title: positive feedback and a runaway greenhouse effect Touisiau 01:54, 23 November 2006 (UTC)

Thank you very much for including the Runaway Greenhouse Effect topic. Two years ago, I could not find any scientific research covering this topic. As global temperatures continue to increase, it becomes extremely relevant to the real-world. --Diego Bank (talk) 21:57, 1 January 2008 (UTC)

Based on this table

Gas removed	percent reduction in GE
H₂O	36%
CO₂	12%
O₃	3%

(Source: Ramanathan and Coakley, Rev. Geophys and Space Phys., 16 465 (1978)); see also [1].

Maybe we should add a crucial information that global warming is inevitable because even if we could remove CO₂ completely from the atmosphere (which we couldn't), we couldn't remove all water vapor from the atmosphere. Meaning that even if we all stopped driving cars tomorrow, the Antarctica will still melt down to water by 2050. --Koramil 02:25, 9 January 2007 (UTC)

Simply because they cause the greenhouse effect doesn't mean they'll cause global warming. If it weren't for other factors, the world would stay at a steady temperature if the amount of greenhouse gases stayed constant. Those gases are needed to keep the earth at a steady temperature, without them we'd be up an average of 30^oC colder. That would suck. Don't blame greenhouse gases for doing their job, they're not the problem. --Calibas 05:36, 9 January 2007 (UTC)

nonsense

The greenhouse gas theory is nonsensical. If carbon dioxide and water vapor reradiate some IR back to us, then the molecules are likewise reradiating out some of the incoming IR from the sun. These molecules are just as likely to cool us as warm us. It makes much more sense to me to blame temperature variations on the source of the radiation. The sun. —The preceding unsigned comment was added by 132.5.72.9 (talk) 22:56, 14 February 2007 (UTC).

That's nice, I always like to get input from people who obviously know nothing about the basic physics of the subject, aren't motivated to research the subject, and aren't ashamed to demonstrate their stubborn refusal to learn anything. Gzuckier 18:26, 15 February 2007 (UTC)

Is that all you have to say Gzuckier? Apart from the IR reradiation not being a logical reason for warming the planet, carbon isotopes and oxygen isotopes found in sediments indicate that carbon dioxide levels do not correlate to climate. 450 million years ago, the Earth was in the middle of an ice age and carbon dioxide levels were significantly higher than they are today. Even more importantly, the carbon dioxide levels were consistently high for millions of years as the Earth's climate oscillated between hot and cold. This alone seems to disprove the whole greenhouse gas theory.

http://en.wikipedia.org/wiki/Image:Phanerozoic_Climate_Change.png

http://en.wikipedia.org/wiki/Image:Phanerozoic_Carbon_Dioxide.png132.5.72.9 18:12, 20 February 2007 (UTC)

Sorry, User:132.5.72.9, but you've misunderstood the basic science. Incoming radiation from the sun is at different wavelengths - principally in the visible part of the spectrum - and the atmosphere is basically transparent to those wavelengths. It's the difference in effective temperature between the incoming solar and the outgoing terrestrial radiation that makes the greenhouse effect exist.

There is a whole body of science on this that is very well developed. If you are serious about understanding the science, here's a link to an online draft of a textbook on this. Pierrehumbert goes through all the steps in a clear and thorough way. Although I'm afraid there is a lot of math needed, you could skip the equations and still get a lot out of the narrative:

http://geosci.uchicago.edu/~rtp1/ClimateBook/ClimateBook.html

As for the phanerozoic, we have only the thinnest of clues what the earth was like that long ago. I think a more relevant comparison is the last 1 million years, during which CO2 and temperature are very tightly correlated. Correlation doesn't prove causation, but it certainly is consistent with it. But the history is not the only basis for the greenhouse theory - there is basic physics behind it, as Pierrehumbert explains.Birdbrainscan 03:56, 4 March 2007 (UTC)

There is also a large body of science on people who read an article or two on a subject, and then are motivated not only to believe that they know more than the entire body of individuals who have studied it professionally all their lives, but to tell all the world that those people are just "nonsensical". (Note that even the folks who oppose the AGW theory don't cite "then the molecules are likewise reradiating out some of the incoming IR from the sun. These molecules are just as likely to cool us as warm us." as an argument). It's nice that wikipedia gives these folks a forum. Gzuckier 16:26, 5 March 2007 (UTC)

First of all, if you think the sun doesn't send IR our way, maybe you should review basic science. Second, the atmosphere is not transparent to the visible spectrum. Have you ever seen a cloud? Finally, variations in carbon mearsurements are taken into account. That's why several models are compared and ALL models indicate higher levels of atmospheric carbon dioxide between 400 and 500 million years ago. During which time the earth experienced the harshest ice age of the past half billion years. If you want to tell me that our dating methods are off by more than 100 million years, then you belong to the ranks that believe evolution is fiction and the earth is only thousands of years old. 132.5.72.9 18:31, 5 March 2007 (UTC)

The earth does receive IR from the sun; in fact, about half of solar radiation is in the near-IR. But the relevant physics are totally different than for the longer-wavelength IR emitted by the earth, and there's so little overlap in the wavelengths of solar and terrestrial radiation that they need to be considered as two completely different streams. Raymond Arritt 18:54, 5 March 2007 (UTC)

Gzuckier 18:07, 6 March 2007 (UTC)
TEMPERATURE (Kelvin)	740 to (3,000-5,200)	(92.5-140) to 740	(10.6-18.5) to (92.5-140)
WAVELENGTH (microns)	(0.7-1) to 5	5 to (25-40)	(25-40) to (200-350)
SPECTRAL REGION	Near-Infrared	Mid-Infrared	Far-Infrared

Water vapor has several absorption bands in both streams. It doesn't send temperatures in one direction. Instead the greenhouse gas keeps temperature balanced. Cloud cover has a net cooling effect, so even if our minuscule contribution of carbon dioxide brought temperatures up, increased water vapor and cloud cover would balance it out. 132.5.72.9 17:27, 6 March 2007 (UTC)

Look, if you're trying to convince us you're an expert, it's not working. Gzuckier 18:07, 6 March 2007 (UTC)

No, you're wrong. Anon is an expert is the special branch of science where all effects are equal and opposite, regardless of mechanism, and all equations are written with binary coefficients. The technical translation of "would balance out" is "has opposite sign". Since the only coefficients in the system are +1, 0, and -1 any pair of numbers with opposite sign cancel to zero. MaxEnt 18:43, 8 April 2007 (UTC)

Technically, those would be Balanced ternary coefficients. --njh 19:25, 9 April 2007 (UTC)

Can I suggest...

Can I suggest that the following sentence (in "Anthropogenic greenhouse effect"):

"Because it is a greenhouse gas, elevated CO2 levels will increase global mean temperature"

is an uncorroborated assertion, i.e. a mere opinion without basis. The reference to the Science article refers to a correlation between rising temperatures and increases in CO2 levels. This does not equate with causation. Pearcedh 19:46, 9 March 2007 (UTC)

Not really. But the text around it could do with some changes William M. Connolley 20:51, 9 March 2007 (UTC)

as it stands, this statement "Because it is a greenhouse gas, elevated CO2 levels will increase global mean temperature" IS a theory. therefore why is the first users edit so bluntly denied?

I agree totally with Pearcedh´s statement. This becomes more evident when we know that IPCC correlates the increase of CO2 from 1960 to ~2000 isolately with the increase in temperature of that period, but just in that same period the cloudiness also increased (see this at http://noparadoxes.tripod.com). —Preceding unsigned comment added by 189.10.214.45 (talk) 22:46, 29 November 2007 (UTC)

This is no more of an unfounded assertion than that photons carry the electromagnetic force. It's based on the best science we have—and there are plenty of reliable sources to support it. Ben Hocking ^{(talk|contribs)} 23:31, 29 November 2007 (UTC)

The student Ben Hocking´s (seems to enjoy fighting as in the hockey games) argumentation has no fundament. There is nothing to do his statement with the historical increase in temperatures, which cause even the IPCC cannot prove that the CO2 is the unique responsible for.

Of course not, since (a) there is no proof in science, and (b) we all know that CO2 isn't the unique cause. You have actually read - or at least skimmed - the IPCC reports that you presume to disagree with, haven't you? William M. Connolley 23:27, 30 November 2007 (UTC)

(a) In true science there are lots of proofs, however not in empiricist science. So, as you think that in such science there are no proofs, how do you defend the "exact" IPCC´s soothsayings for a time 100 years (!) ahead?? Don´t you think that the true science do not allow such previews?

In the article http://noparadoxes.tripod.com there are lots of scientific proofs.

After glancing over that web article I have little response to add, although I wish to state that I have no comment. Raymond Arritt (talk) 20:55, 6 January 2008 (UTC)

First paragraph

The greenhouse effect, discovered by Joseph Fourier in 1824 and first investigated quantitatively by Svante Arrhenius in 1896, is the process in which the emission of infrared radiation by an atmosphere that warms a planet's surface.

There is a grammar error here. Two brownies and a gold star for the first successful fix! --Uncle Ed 17:04, 21 March 2007 (UTC)

Sandbox proposal

A sandbox for contributors to try out different introductions to the article is here:

/intro

Note that this is not intended as a "branch" but as a showcase for various competing versions. The 3RR does not apply to it, because it is a sandbox.

When a sandbox version gains consensus, it can replace the current intro. --Uncle Ed 17:09, 21 March 2007 (UTC)

Greenhouse_effect#Real_greenhouses

To altitude 11km is the temprature not determineted per radiation, but the convection. The the absorbed radiation reduced the convection heat flux, but not change the temperature. Over 11 km ist the temperature determined be radiation balance. Excuse me my english. --217.82.191.244 12:12, 17 May 2007 (UTC)

Reflected light

The Earth receives energy from the Sun in the form of radiation.
The Earth reflects about 30% of the incident solar flux;

I'm wondering, what becomes the radiation which has been reflected from Earth to Universe? Does it just lights out the planet or something? Or can it be re-used for hem... other purposes? (it's only a curious question, but the curious are never answered... if you know the answer, spend time for humanity and free encyclopedia and such... and click edit button to answer me) 194.199.142.126 14:43, 25 May 2007 (UTC)

Main article - global warming?

Global warming is certainly not a main article of greenhouse gases.. WinterSpw 05:56, 12 June 2007 (UTC)

Agreed William M. Connolley 08:23, 12 June 2007 (UTC)

We need some more feedback here. WinterSpw 04:22, 15 June 2007 (UTC)

"greenhouse gases" section needs a rewrite

I'm not too jazzed about this explanation of how the greenhouse gases absorb IR light, especially the part about the "floppier" molecules contributing more. Then again, I'm not sure how intelligible everyone wants this article to be to the layperson. (I'll get technical for a second and then move on to my point) Just so we're all clear, the criterion for absorption of IR light by a molecule is that the dipole derivative of the vibrational mode to be excited in that molecule is nonzero (at least within the dipole approximation). "Floppier" has little to do with it: carbon monoxide, if it were present in large quantities (and thank God it's not), would be an important contributor to the greenhouse effect as well, because stretching the C-O bond changes the dipole moment of the molecule (nonzero dipole derivative). And CO is probably one of the least "floppy" molecules around.

Okay, technical stuff over. If we want the article to be technical, this stuff should certainly be in there. I was under the impression, however, that the article should be at least somewhat accessible to the layperson with a passing interest in science. In that case, maybe it would be more conceptually efficacious to throw in a little graphic of a molecule vibrating, with maybe an arrow or something representing the dipole changing over the course of a vibrational period. This would be especially effective with CO2: showing the symmetric and asymmetric stretches side-by-side and illustrating that the asymmetric case is the one for which the dipole changes and hence is IR-active, whereas the symmetric stretch is not.

Anyway, just a suggestion.

PS--I also realize that larger molecules do have more vibrational modes and would also contribute appreciably to the greenhouse effect were they present in the atmosphere in any significant quantity. I'm just concerned that the layperson would read this and misunderstand the mechanism at work here. Sorry, I'm a spectroscopist--it's my bread and butter.

I suggest you have a go - make it technically correct but still readable William M. Connolley 08:22, 14 June 2007 (UTC)

Interesting article

I recently came across an interesting article and a possible source to be used for this article in the 1955 Monthy Weather Review. — jdorje (talk) 04:41, 31 August 2007 (UTC)

You're right, it is indeed interesting, from a historical point of view William M. Connolley 08:54, 31 August 2007 (UTC)

Have the laws of physics relevant to climate science changed significantly since 1955?Gordon Vigurs 07:02, 11 September 2007 (UTC)

An odd question. Did you read the article? The answer is, no, obviously not; but we now have the Mauna Loa record of CO2, and measurements from ice cores William M. Connolley 08:24, 11 September 2007 (UTC)

Would an article on 'timeline of greenhouse effect knowledge' be a good idea? Sounds like a useful reference to me to allow answers of the 'but this is well established for xx years' type. It probably wouldn't work out that way as lots of information slowly gets firmed up over many papers and including them all wouldn't be reasonable. crandles 10:53, 11 September 2007 (UTC)

Sorry, just a bit of unseemly sarcasm, please feel free to delete. This article is very important, but insufficient to inform the layman of the most important issue - how accurate are the predictions? Few people are impressed with systems which only predict past events. And the brow-beating style of some of the above comments give the impression of Emperor's New Clothes. Could we have, for example, the mean temperature for July 2010 in London, corresponding to a range of different environmental policies, to demonstrate that current models can indeed predict future events.Gordon Vigurs 12:41, 12 September 2007 (UTC)

The article isn't about predictions. You want global warming for that. July 2010 is weather, not climate William M. Connolley 13:56, 12 September 2007 (UTC)

Nevertheless (although William is correct that this is off-topic), here are two articles that deal with predictions: [2] [3]Ben Hocking ^{(talk|contribs)} 14:00, 12 September 2007 (UTC)

All legitimate science is about predictions. The theory which fails to predict future events is discarded as false, or demonstrated to be a special case of a more general theory. If it is not about prediction, it is not about science. In view of the infallibility clained for current climate modeling, it appears reasonable to expect precise predictions, with identifiede error bounds.Gordon Vigurs 07:48, 16 September 2007 (UTC)

You're still on the wrong page guv. The predictive elements of GHE and/or climate modelling are... where you've been pointed to. The stuff here is a part of radiative physics, which does indeed make well tested predictions. You're wrong that all science must make predictions, unless you want observational astronomy or ecology to be non-science; something the Popperians might do I suppose. Oh, and "infallibility" is silly, of course William M. Connolley 08:43, 16 September 2007 (UTC)

Parasol Effect

The processes of global warming presented are incomplete. The effect of atmospheric aerosols and dust cannot be ignored. Gordon Vigurs 10:41, 6 September 2007 (UTC)

In describing the earths climate, no. In describing the GHE, yes. You may want global warming or global dimming William M. Connolley 10:47, 6 September 2007 (UTC)

Thanks - these are both interesting articles Gordon Vigurs 10:52, 6 September 2007 (UTC)

Radiation Diagram

Can anyone confirm that the diagram at the top of this article really represents the Greenhouse Effect? If it does then I think that at the very least this represents a major breach of the 2nd law of thermodynamics. There is no doubt that, on a global scale, the lapse rate ensures that the troposphere is cooler than the surface, how then is this cooler troposphere able to radiate 324W/m2 to the surface? When this reaches the surface it is absorbed 100%, not possible! If there is something I have missed then please tell me, but the science of thermodynamics describes heat transfer and this diagram appears to drive a coach and horses through the 2nd law. I propose to place a statement to this effect at the top of the article in a prominent position, a sort of smoking warning! Damorbel 15:51, 16 September 2007 (UTC)

324 atmosphere to earth is less than 452 from earth to atmosphere. That is the way round I would expect. The atmosphere shows 519 in and out also as I would expect. Of 519, 324 goes to earth and 195 to space. Obviously this is not showing heat transfers within the atmosphere so you 100% doesn't seem to be a problem to me. crandles 17:11, 16 September 2007 (UTC)

In my opinion, there are many problems with that image - but, if you know those limitations the image can still be very useful. As for the planet absorbing 100% of the energy from the atmosphere, I think we have to assume that the atmosphere is actually radiating more than indicated but that only 324W/m2 are actually absorbed. What I find interesting is that more heat is shown coming from the atmosphere than from the sun.

As for the lapse rate, that's one of the problems with images of this type. I would prefer an image that shows the contributions of various parts of the atmosphere. For instance, using the "Earth standard" lapse rate of 6.5°C/km, a temperature drop of 33°C (the temperature increase produced by the Green House effect) represents only 5km (~16,000ft). Since 11km (~36,000ft) is usually considered the top of the troposphere and because the troposphere is heated primarily by convection, not radiation, it would be useful if the image showed convection and radiation effects separately instead of lumping them together.

I have a related question - The article says

The Earth reflects about 30% of the incoming solar radiation. The remaining 70% is absorbed

But the image caption says (click on the image to see this)

Direct overhead sunlight at the top of the atmosphere provides 1366 W/m2; however, geometric effects and reflective surfaces limit the light which is absorbed at the typical location to an annual average of ~235 W/m2.

Well ... 235/1366 indicates (to me) that only about 17% is absorbed, not 70%. Can someone please explain this? Q Science 02:40, 17 September 2007 (UTC)

The 1366 W/m2 value is for a beam perpendicular to the earth (it's typically called the "solar constant", though it isn't precisely constant). At latitudes above the equator the beam won't be perpendicular, and on the dark side of the earth the beam won't be there at all. Quantitatively, we account for this by scaling the solar constant by the ratio of the area of a disk to the surface area of a sphere. The area of a disk is pi*r^2 while the surface area of a sphere is 4*pi*r^2, so the ratio is simply 1/4. Multiply 1366 W/m2 by 1/4 to get the mean irradiance over the earth; this works out to 341 W/m2. Now multiply this by 0.7 to get the fraction that is absorbed and you end up with 239 W/m2 which is essentially the stated value of 235 W/m2. I just gave away the answer to a classic homework problem, but what the heck... Raymond Arritt 02:51, 17 September 2007 (UTC)

Thanks - I suggest adding that to the image description on Image:Greenhouse Effect.png Q Science 03:43, 17 September 2007 (UTC)

Solar Spectrum Image not Displaying at 350px

The image Solar Spectrum.png is not displaying in my IE browser when the size is given as 350px. It does display with a size of 400px and 500px. Note that the image size is actually 800×595. I don't know if it is just my system or a more general problem.

Image:Solar Spectrum.png|thumb|350px|right|text here ....

Pages with 350px - Greenhouse effect Solar variation
Pages with 400px - Solar radiation
Pages with 500px - Sunlight

I did try editing the tag, and the size was the only thing I had to change to see the image. Currently, on both 350px pages, all I see is a white box and the caption. Q Science 16:28, 17 September 2007 (UTC)

I checked all 4 pages with IE on two other machines and they all display correctly. Is it just my system, or are others having the same problem? Q Science 19:15, 17 September 2007 (UTC)

Removing gasses table source

If Water vapour: feedback or forcing? is going to be used as a reference, then that should be said as the source. So I made everything match what the reference says. While I don't doubt that Dr. Connolley's knowledge of what's in Ramanathan and Coakley (1978) the reference is not to it.

If the reference is changed to the paper, Ramanathan, V. and J. A. Coakley, Jr., 1978: Climate Modeling through Radiative-Convective Models. Rev. Geophys. and Space Physics, 16: 465-490. http://www-ramanathan.ucsd.edu/publications/Ramanathan%20and%20Coakley%20RevGSP%201978.pdf that's fine too. (Sorry if I did that backwards, I didn't find the actual paper before I changed the article.)

In any case, it all matches now, number, source, reference.

Actually, the reference says

CO2 alone makes up between 9 and 26%

so the 12% (that you removed) was kind of an average. Q Science 17:57, 25 October 2007 (UTC)

I'd also like to see Clouds and Other GHG added to the table, but I don't know if that's needed. Sln3412 21:26, 24 October 2007 (UTC)

No, CO₂ alone absorbs 26% (IPCC 25%) of the total. The reference shows that with RC78, removing CO₂ leaves the GE -12%, while the 2005 ModelE leaves the GE at -9%. CO₂ is 25/26 if it's the only component left, not the only one removed.

So they are two different things; no CO₂ is 9%/12%, CO₂ by itself is 25%/26%. The chart shows two different situations, removing something from the whole versus using one thing alone.

As another example, the chart at Real Climate shows removing O₃ absorbs 3%, but O₃ as the only factor absorbs 7%.

It's like asking if there's 10 apples, and you take 3, 'how many are left' or 'how many do you have'. They don't mix, the first question's answer is 7 and the second 3; you can't put the two questions together and get the answer of 5 using the median or mean of 7 and 3. Sln3412 20:09, 26 October 2007 (UTC)

Thanks for the clarification. I would have never gotten that without a little help. The text in the reference (quoted above) did not suggest that interpretation. I suggest also changing removal of both of these constituents will be greater than 45% to will be 47% to be less ambiguous. Q Science 05:05, 27 October 2007 (UTC)

Celsius-Fahrenheit confusion

Due to the recent confusion identified on RealClimate[4], I added the Fahrenheit conversions in the introductory paragraph, which will allow the Celsius-challenged to read this article without puzzlement. I hope this is fine with the rest of you. Iceberg007 03:53, 13 November 2007 (UTC)

Good idea. Raymond Arritt 03:58, 13 November 2007 (UTC)

So was this [5] William M. Connolley 16:10, 13 November 2007 (UTC)

I agree! :P Iceberg007 21:22, 13 November 2007 (UTC)

Uhh am i missing something or do both temperatures show 59'F?

33C is 91.4F —Preceding unsigned comment added by 91.105.43.151 (talk) 17:43, 13 March 2008 (UTC)

Vandalism

Woo, lots of kiddos with spray cans today on this one. Cheers for those who beat it down better than I =) Ryo 18:47, 13 November 2007 (UTC)

Experimental Evidence

There are innumerable theoretical calculations and climate models that either allude to or rely upon the greenhouse effect. However, in all of these there does not appear to be any reference to experimental confirmation of the theory. I know that there has been voluminous discussion about real greenhouses and the greenhouse effect but is there a defining experiment that confirms the theory? If so, should it not be at least referenced in the article? —Preceding unsigned comment added by 69.244.42.213 (talk) 18:54, 29 January 2008 (UTC)

Depends what you're looking for. Obviously, we won't get to test what a planet otherwise like earth but with no GHG, or no CO2, in the atmosphere behaves like. There is any amount of basic radiative physics that the GCMs use to build their radiative codes; I've never read that stuff and anyway I doubt it would be very useful here William M. Connolley (talk) 20:53, 29 January 2008 (UTC)

I'm looking for something like the experimental verification of, say, Planck's law or the Stefan Boltzmann law where the theory predicts the outcome of an experiment. Is there such a laboratory experiment? I can think of a general scheme where two strong transparent canisters, one containing CO₂ and the other containing N₂, are suspended on a fine string inside a vacuum chamber and illuminated with a heat lamp while measuring the temperature over time. Has something like this not been done? —Preceding unsigned comment added by 69.244.42.213 (talk) 20:43, 30 January 2008 (UTC)

Not quite what you want, but http://www.wmconnolley.org.uk/sci/wood_rw.1909.html is somewhat relevant. At the level of basic level of radiative physics, the experiment you describe would be pointless, because the results are known. It might be done at high school or by undergrads just to demo theory, but it wouldn't be done as publishable science, at least not nowadays. I'll point a radiative friend at this page and see if he has anything to say William M. Connolley (talk) 20:51, 30 January 2008 (UTC)

The greenhouse effect is an issue of radiative energy transfer as William said. A useful place to look would be if we can model emissions from the earth as observed in space. Take a look at http://www.sp.ph.ic.ac.uk/~gerb/gerbteam/GERBProject_JEHarries_BAMS_revised.pdf

This is more on point but it is behind a paywall http://adsabs.harvard.edu/abs/2001Natur.410..355H

There are other place, but that seems the best to answer your questions. Much of the work was done based on measurements from the ATMOS instrument that was flown on Skylab and the first shuttle missions.

Combining a radiation transfer code like FASCODE or MODTRAN with a GCM or a weather model and out pops the greenhouse effect. Things are not perfect (for one thing the number of levels in the models is pretty low) but they are good enough to answer your question positively. —Preceding unsigned comment added by Jhalpern (talk • contribs) 03:04, 31 January 2008 (UTC)

Hmm...I guess if you want something done...I'll set up that high school experiment and see what I get. By the way, since we know what the results will be, what will the results be? —Preceding unsigned comment added by 69.244.42.213 (talk) 14:54, 31 January 2008 (UTC)

Not very much interesting because you can't isolate the gas from the walls, which will exchange energy by radiation and conduction. —Preceding unsigned comment added by 138.238.33.67 (talk) 18:17, 31 January 2008 (UTC)

If you shine IR through two gases, one of which absorbs IR and the other doesn't, then the one that absorbs IR will get warmer. Exactly how much depends on how strong the IR is, how thick the gas is, and how fast it loses the energy William M. Connolley (talk) 20:32, 31 January 2008 (UTC)

By doing the experiment in a vacuum chamber, the conduction/convection should be essentially eliminated. Radiation from the walls of a container should not have a greater effect than radiation from non-greenhouse gases in a planets atmosphere. It would not be a viable experiment if one used an IR laser tuned to the absorption line of the greenhouse gas. I will need to use a blackbody source (heat lamp) to get something that can represent the system of interest, i.e., a planet's atmosphere under solar illumination.

I was looking for something a little more quantitative, William. Perhaps my question was too vague. :) —Preceding unsigned comment added by 69.244.42.213 (talk) 15:55, 1 February 2008 (UTC)

The infrared source (emitter) creates a high-intensity stream of energy incorporating all wavelengths in the infrared spectrum.

The stream passes through the optical filter, which blocks all wavelengths except those that CO2 absorbs. The filtered infrared energy strikes the detector and causes it to heat up. When CO2 is drawn through the sampling cell by the D-TEK CO2’s internal pump, some of the infrared energy is absorbed by the CO2. This causes a decrease in the amount of infrared energy reaching the detector and a corresponding drop in the detector’s temperature, which triggers the D-TEK CO2 to alarm. This whole process takes a fraction of a second.

By utilizing an optical filter with precise characteristics, INFICON has made D-TEK CO2 sensitive to CO2 while minimizing false alarms. In addition, the detector recovery time is also immediate after the CO2 clears the cell.

http://www.inficon.com/download/en/D-TEK_CO2.pdf Gzuckier (talk) 16:38, 1 February 2008 (UTC)

Wikiproject Earth

Hello i have recently proposed the Wikiproject Earth. This Wikiproject`s scope includes this article. This wikiproject will overview the continents, oceans, atsmophere and global warming Please Voice your opinion by clicking anywhere on this comment except for my name. --Iwilleditu ^{Talk :)}^{Contributions} —Preceding comment was added at 15:37, 30 March 2008 (UTC)

Reason being

the reason for these greenhouse gasses is the uneven heating of the earths serface —Preceding unsigned comment added by 24.46.165.19 (talk) 23:14, 31 March 2008 (UTC)

Faint young Sun problem has been solved

See here

Warming the early Earth - CO2 reconsidered Authors: P. von Paris (DLR), H. Rauer (DLR, TUB), L. Grenfell (DLR, TUB), B. Patzer (TUB), P. Hedelt (DLR), B. Stracke (DLR), T. Trautmann (DLR), F. Schreier (DLR) (Submitted on 25 Apr 2008) Abstract: Despite a fainter Sun, the surface of the early Earth was mostly ice-free. Proposed solutions to this so-called "faint young Sun problem" have usually involved higher amounts of greenhouse gases than present in the modern-day atmosphere. However, geological evidence seemed to indicate that the atmospheric CO2 concentrations during the Archaean and Proterozoic were far too low to keep the surface from freezing. With a radiative-convective model including new, updated thermal absorption coefficients, we found that the amount of CO2 necessary to obtain 273 K at the surface is reduced up to an order of magnitude compared to previous studies. For the late Archaean and early Proterozoic period of the Earth, we calculate that CO2 partial pressures of only about 2.9 mb are required to keep its surface from freezing which is compatible with the amount inferred from sediment studies. This conclusion was not significantly changed when we varied model parameters such as relative humidity or surface albedo, obtaining CO2 partial pressures for the late Archaean between 1.5 and 5.5 mb. Thus, the contradiction between sediment data and model results disappears. Comments: 55 pages, 4 tables, 11 figures, accepted in Planetary and Space Science Subjects: Astrophysics (astro-ph) DOI: 10.1016/j.pss.2008.04.008 Cite as: arXiv:0804.4134v1 [astro-ph]

Count Iblis (talk) 00:48, 29 April 2008 (UTC)

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