Talk:Atmosphere of Venus

From Wikipedia, the free encyclopedia

Atmosphere of Venus has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do. If it no longer meets these criteria, you can delist it, or ask for a reassessment.

April 30, 2008

Good article nominee

Listed

Space Portal

This article is within the scope of WikiProject Space.

This article has been rated as GA-Class on the assessment scale.

Related projects:

WikiProject Astronomy

WikiProject Solar System

Help with this template

This article has been rated but has no comments. If appropriate, please review the article and leave comments here to identify the strengths and weaknesses of the article and what work it will need.

	This article related to meteorology and/or specific weather events is part of WikiProject Meteorology and Weather Events, an attempt to standardize and improve all articles related to weather or meteorology. You can help! Visit the project page or discuss an article at its talk page.
GA	This article has been rated as GA-Class on the assessment scale.
Mid	This article has been rated as mid-importance within WikiProject Meteorology.

I made some minor changes to references; I also deleted a sentence that mentioned the albedo of Venus is 0.76, since one sentence later it stated that Venus reflected 90% of the incident sunlight. The alternative to deleting this sentence would have been a long discussion of the different types of albedo (which varies with wavelength), which would have been rather off topic; people actuallly interested in albedo can look at the albedo entry.

Geoffrey.landis 15:13, 12 September 2006 (UTC)Geoff Landis

1 hydrogen can easily be extracted
2 How hot is Venus?
3 Extreme cold! (Brrrhh!)
4 Good article nomination
5 Survey
6 GA review
7 Good Article assessment

[edit] hydrogen can easily be extracted

"Hydrogen is primarily present as sulfuric acid (H2SO4), and hydrogen can easily be extracted through condensing the droplets."

Sulfuric acid does not release any hydrogen by "condensing" the droplets. On the contrary, sulfuric acid attracts and holds any water violently. Perhaps this is the reason why there is any trace of water on Venus left at all. 84.160.239.47 22:17, 17 November 2006 (UTC)

Fixed. --Xanthine 12:30, 3 January 2007 (UTC)

The article has several apparent contradictions which need to be explained in footnotes if not the main text ie "sulpher dioxide is 150 parts per million." No mention of sulpher trioxide which should be in surplus if there is "no water." It says 6 parts per million of water vapor in another part of the article. I suppose the problem is the composition of Earth's atmosphere is typically given as gas only and particulates such as dust, sulpheric acid, ice and water droplets are discussed separately. Also, Earth atmosphere scientists typically include the carbon dioxide vapor percentage, but not the water vapor percentage; just the opposite of how we have figured Venus, perhaps because the lower atmosphere of Venus is hot enough that carbon dioxide is a gas, not a vapor, as it is in Earth's atmosphere. Neil

The text includes the conjecture that Venus' atmosphere is composed of largely carbon-dioxide and nitrogen mixture because of the lack of a strong magnetic field, lighter gases not being held because of the lack of a strong magnetic field as Earth has. That would hold true also for Mars, which has a largely carbon dioxide-nitrogen atmosphere (if much thinner).

A simpler explanation exists: Venus is hot. Magnetic fields do not hold gases so effectively as does gravity. The Earth has high enough gravitation and cooler temperatures to hold gases as light as methane, ammonia, and water vapor. To be sure, the Earth's atmosphere holds little methane or ammonia because of thermodynamic instability in an oxygen-rich environment, but it holds water vapor very well. It's, of course, gravitation. A strong magnetic field may prevent some chemical reactions in the Earth's upper atmosphere, preventing the formation of such substances as sulfuric acid, but that is a different topic.

Venus is much hotter at its surface, hot enough that with gravity slighter (but not by much!) than the Earth's, Venus cannot hold gases as light as methane, ammonia, and water vapor. Much chillier than Earth, but with far lesser gravity, Mars likewise cannot hold water vapor. With their combinations of temperature and gravitation, both Mars and Venus can hold atmospheres consisting largely of carbon dioxide and nitrogen. --Paul from Michigan 01:49, 25 November 2006 (UTC)

If proponents of Gaia theory are to be believed, a major reason for the water on Earth is due to the abundant presence of life. Indeed, all living things capable of aerobic respiration produce water as a matter of discourse. Venus and Mars, on the other hand, have atmospheres relatively close to their equilibrium states (Mars more so than Venus). Interestingly enough, Lovelock discusses this in the first of his Gaia books, calculating that if Earth were to be left to form an equilibrium state (ie: if all life were somehow wiped out), it's atmosphere would be ~95% carbon dioxide and it's surface temperature would be in the region of 250 centigrade. Makes you think, doesn't it...? --Xanthine 12:30, 3 January 2007 (UTC)

Life is of course a non-equilibrium state. Under equilibrium, water would react with carbon and carbon compounds to form carbon dioxide, and with sulfur and sulfur compounds to form sulfuric acid. As is well known one can place carbon and sulfur in cold water and have no reactions.

Biochemistry itself suggests that life formed on Earth from a mixture of substances, some of which would not exist long in an oxygen-rich environment. Of course, water, carbon oxides (whether carbon monoxide or carbon dioxide), and phosphates exist. But most biochemical substances are methane derivatives. Ammonia and hydrogen sulfide would have to have existed.

Living things (plants) can synthesize methane derivatives from carbon dioxide and water and can transform mitrites and nitrates into ammonia. Some bacteria 'fix' mitrogen. But that is life at work.

Most predictions of the future of the Earth suggest that as the sun becomes more luminous, that unless the Earth's orbit becomes adequately displaced from where it is now (I believe that if humanity or some intelligent successor is around, that creature is likely to force the Earth into orbitd progressively more distant from the sun as needed), the Earth will get hotter. The Earth is toward the warm end of the life zone, and when the normal temperature on Earth approaches 45C, life will be in big trouble. Much of the biomass will die and become fuel for spectacular forest and brush fires that will thrust more carbon dioxide into the atmosphere, accelerating global warming. Higher evaporation of water will have added another greenhouse gas -- water vapor -- into the atmosphere. Atom for atom, water vapor is an even more powerful greenhouse gas.

Around 70C, the 'wet greenhouse' effect that some say occurred early on Venus takes off, and the Earth's atmosphere itself takes on the characteristics of a pressure cooker. Meanwhile, the greater pressure of the atmosphere causes the atmospheric temperature to rise in accordance with the gas laws. The process accelerates as more of the waters of the sea evaporate into the atmosphere. Some water vapor goes to the upper atmosphere and some water molecules dissociate into oxygen and hydrogen, hydrogen going off into space. Until the seas are evaporated away, there's more water vapor available to replace the water dissociated into oxygen and water.

At 305 C, the critical temperature of water, liquid water no longer exists. By then, even if the Earth has gigantic clouds protecting the planet from sunlight, pressure alone creates hothouse conditions. (Venus is hot because of the pressure of its atmosphere -- not because of the intense sunlight that shines upon cloud layers that insulate the planet). Carbonate rocks dwxompose, releasing carbon dioxide, and pressures lead to temperatures high enough to melt surface rocks.

Gory, isn't it? The earth's atmosphere would be full of oxygen from dissociated water, carbon dioxide first from the budning of biomass and petroleum and then especially the release of it from carbonate rocks, sulfuric acid from the burning of sulfur and sulfur compounds, a little nitrogen, and some water vapor. The Earth could get even hotter than Venus is today -- hot enough to melt all rock surfaces. That's all long before the Sun flares off the atmosphere and beats down upon the exposed surface of the Earth.

That all depends upon the extinction of complex life. We might not have the means -- yet -- of altering the Earth's orbit. But humanity or whatever its successor at the time (advanced pigs?) will likely cherish life enough to get the Hell out of an infernal prospect. The Gaia effect got little chance on Venus or Mars. It may need some help a few hundred milliion years hence just to continue. Sure, this is speculation, and as such 'original research'... probably forgivable in a talk page. --Paul from Michigan 10:20, 14 January 2007 (UTC)

Surely speculation is the entire point of a talk page! :) I'd love to continue this conversation, but I fear it'll soon venture too far off topic... --Xanthine 12:57, 23 January 2007 (UTC)

[edit] How hot is Venus?

How much hotter is Venus than Earth?

It's a lot hotter if you compare surface temperatures to surface temperatures -- 288K to 750K. But, if you compare atmospheric temperatures at the same pressures, say at 1 Bar, the difference is a lot less dramatic. Earth's 1 Bar temperature is 288K while Venus' is 360K. If you also subtract out the extra temperature due to Venus having to shed more heat from solar radiation, the difference in atmosphere temperature is around 20 K -- a whole lot less than the almost 500 degree difference in surface temperatures.

This means that the extra heat at the surface is coming from adiabatic compression (extra pressure), not from extra solar radiation or greenhouse effect. I've written up an article explaining this more fully, and posted it at

http://www.whiteworld.com/non-fic/Venus-temp.htm

I'd like to get an external link reference put in this article, if I could.

Cyreenik 15:31, 12 April 2007 (UTC)

Venus is so immensely hot, that a cat on a hot tin roof would stay on the roof, if it just knew how lucky it was. Said: Rursus ☻ 08:37, 29 November 2007 (UTC)

35 km above Venus's surface, the temperature is as hot as a typical baking or cooking oven. (See your cookbooks, if you're in America, there'll probably be quite a few references to 350 degrees Fahrenheit, which translates into 177 degrees Celsius, or 450 Kelvin. I dunno what it's like in other countries.)68.36.214.143 (talk) 00:12, 10 December 2007 (UTC)

[edit] Extreme cold! (Brrrhh!)

There is a "Cryosphere" mentioned at esa.int. It's at 90-120 km height. Said: Rursus ☻ 08:43, 29 November 2007 (UTC)

[edit] Good article nomination

"Looks good" to me, except the last images at the bottom illustrating future missions need to be better sourced. One just says "from NASA", the other says "from university, presumably copied from NASA." Potatoswatter (talk) 21:53, 10 April 2008 (UTC)

I added a direct link to NASA site for the first image. I temporally removed the second one because I can not find it on the NASA server. Ruslik (talk) 05:58, 11 April 2008 (UTC)

[edit] Survey

WP:Good article usage is a survey of the language and style of Wikipedia editors in articles being reviewed for Good article nomination. It will help make the experience of writing Good Articles as non-threatening and satisfying as possible if all the participating editors would take a moment to answer a few questions for us, in this section please. The survey will end on April 30.

Would you like any additional feedback on the writing style in this article?
- No. This article has had many contributors of varying English expertise; the path to clarity is clear. Potatoswatter (talk) 17:07, 12 April 2008 (UTC)
If you write a lot outside of Wikipedia, what kind of writing do you do?
- Technical academic stuff. Potatoswatter (talk) 17:07, 12 April 2008 (UTC)
Is your writing style influenced by any particular WikiProject or other group on Wikipedia?

At any point during this review, let us know if we recommend any edits, including markup, punctuation and language, that you feel don't fit with your writing style. Thanks for your time. - Dan Dank55 (talk) 21:05, 11 April 2008 (UTC)

[edit] GA review

I've signed up to review this, and I'll put comments when I get a chance for a thorough read Jimfbleak (talk) 11:05, 29 April 2008 (UTC)

Intro: see Wikipedia:Lead section. The lead seems the weakest part of the article. It should not exceed four paras, and the current fifth para is just one sentence. The lead gives too much detail in some places (eg percentage of atm. gases), but doesn't mention some of the main headings at all. Intro needs a bit of work. Jimfbleak (talk) 11:19, 29 April 2008 (UTC)

I made a few changes in the lead section. Ruslik (talk) 11:40, 29 April 2008 (UTC)

Consistency and formatting. Careful copy edit is needed

Venusian should be capitalised. Venus' or Venus's? both are used, inconsistent