Talk:Earth's atmosphere

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[edit] Carbon Dioxide as "Air Pollution"?

This is a little far-fetched. There are a huge number of environmental benefits to the existence of CO2 and room for much more in quantity. It's not pollution. --82.43.47.6 (talk) 22:33, 18 February 2008 (UTC)

[edit] Atmosphere composition

I just reworked a few sections. For some reason I was not logged in anymore when I submitted the changes; they were the two changes after the july 18 edit by cos111 (me).

I am not exactly an expert on global warming and climate change, but I think what I did with that is a lot better--better introduction and explanation, and a little more NPOV. user:cos111 2003-07-19

What on earth happened to this article?! Shatha 22:34, 10 March 2006 (UTC)


"Evolution of Earth's Atmosphere" asserts that a molten earth causes an unstable atmosphere. Why? Gas giants have non-solid surfaces and they have stable atmospheres.
There are still some problems here - some minor changes need to be made for clarity's sake, but some genuine factual errors need to be fixed. It was not heat that drove away hydrogen and helium, it was lack of gravity combined with solar wind. If those changes haven't been made when I check back, I'll make them. Otherwise, have at it. Denni 18:20, 2004 Jan 18 (UTC)
...well actually, in order for Helium and Hydrogen(molecules) to become bouyant in an atmosphere they require heat. But in combination with atmospheric conditions which would include things like gravity and external forces... --Hard Raspy Sci 18:36, 11 Feb 2005 (UTC)


Note that even within this region [Ozone layer], ozone is a minor constituent by volume.
Just as well, because otherwise you might die of ozone poisoning if you fell out of a supersonic airplane.

[edit] Units

This article has a mixture of British and US spellings. Not sure which way the article started, but spelling should be changed to one way or the other.

(It's amazing how bad an article looks with a mixture of the two, IMHO)

Duk 23:23, 11 Sep 2004 (UTC)

Looks like someone onece chnged all units from kilometers to miles. Another one reverted changes of the page, but not of the picture. Anyone knows, how to get an old picture back? Or may be it's better to create an image with all units on it? (and also note all the values inside an article with an appropriate notice? - like 10km (16mi)Mihail Vasiliev 18:50, 28 October 2005 (UTC)

[edit] Incorporate from Air

Air was turning into a weak mirror of this article, so I cut its head off and made it a disambig. This is the information that was removed, feel free to incorporate it as is seen fit.

Dry air is roughly 79% nitrogen, 20% oxygen, and 1% argon. Air may contain 0-7 % water vapor (the 79%, 20% and 1% become accordingly a little less), and less than 1% carbon dioxide. The composition of air changes with altitude; also exhaled air contains a greater percentage of carbon dioxide than what is inhaled, ca. 4.5%.

There is a more accurate chart athttp://education.jlab.org/glossary/abund_atmos.html.

Pressure decreases with altitude; this is why aircraft have pressurised cabins. The air pressure inside aircraft cabins is maintained at a pressure higher than that outside, for the comfort of the passengers and crew, although for fuel efficiency reasons the pressure is still slightly lower than at ground level. With a decrease in total air pressure, the partial pressure of all the component gases (including oxygen) decreases. Mountain climbers must carry a supply of oxygen on their way up to the summit of high mountains to ensure the partial pressure of oxygen in their blood is maintained.

--Ben Brockert 01:21, Oct 21, 2004 (UTC)

[edit] Composition table

The composition table is misleading and a bit redundant. The totals given indicate 9 significant figures - far more precision than is possible. The totals thus are misleading and should be eliminated. If we don't worry about the fictitious total then we don't need the Normalized to 100% column at all (doesn't total to 100% anyway) it is meaningless. I would recommend following the NASA site used as a source and give the minor compnents in ppm thereby eliminating all those meaningless zeros and any need for totalling. CO2 and methane are indeed quite variable both spatially and temporally and the values given are only an average. I plan to modify the table drastically unless someone can present good reasons to keep it as it is. Vsmith 04:51, 1 Jan 2005 (UTC)

The "per NASA" part of the table has the same number of signifcant figures as the NASA page; the other column has two more sig figs for each number, otherwise the adjustment doesn't get it much closer to 100%. The adjusted figures were used to create the pie chart. Reporting the numbers in percent and PPM is inelegant. --—Ben Brockert (42) UE News 06:35, Jan 1, 2005 (UTC)
Removed un-needed normalized column (noted the normalization in the figure caption). The values in the figure are misleading in that they imply a Andrew K Robinson 01:59, 14 August 2007 (UTC)greater precision than is justified by the data. Please review the meaning and rules for significant figures. The total is now to correct # of sig. figures, but as noted above is rather misleading due to variability noted and should probably be cut. As for ppm and elegancy - nonsense. Should be as ppmv. Perhaps the inelegancy of ppmv would negate the perceived need for a 100% total. I may return to rid this mis-leading elegance :-) -Vsmith 03:38, 6 Feb 2005 (UTC)
If you change some of the values from the reference, you need to adjust the others. As CO2 increases the fraction of O2 and N2 decrease in the last digit. This should at least be noted. Archimerged 14:42, 15 January 2006 (UTC)

COMMENTS: BIOL 1409.2426 (Student Joseph Cahill): (State your opinion of the need or lack of need to be more environmentally friendly).

It is my opinion that we MUST become more environmentally friendly immediately! Simple steps can be taken everyday by anyone who make this a priority. Recycling is the easiest way to begin to help out. I personally make a point of recycling all plastic, cans and other materials like paper that I can everyday. I have three bins set-up in my house to store and collect the items. I use cloth bags when I shop and ensure every container I use can be recycled.

On the topic of the Global Warning, it is my opinion that society is slowly becoming aware of the need to reduce ozone gases. Baby-steps are being taken by the auto industry to create hybrid and fuel cell cars. The demand for the hybrid cars is mainly based on the increase cost of petroleum gas NOT because suddenly all drivers realize the impact of combustion engines. I wish that the huge sales of the successful Toyota Prius Hybrid were ALL because of environmental concerns, however it is more about the cost of operation. Damage to the Earth's atmosphere has an impact on ALL living things. This is scary because if one link in a food chain is disturbed it affects the entire chain.

  • I agree with you. And I have updated the concentration of CO2 to 380 from 350 as it has changed - The reference may no longer be valid.--Max Randor 12:46, 5 June 2006 (UTC)

Why not simplify the percentages more? Two decimal places would surely be accurate enough for elements that account for more than 0.01%, one decimal place for those over 1%, and integers for those over 10%. And why does the total significantly exceed 100%? --Andrew K Robinson 01:59, 14 August 2007 (UTC)

Did you read reference 2 at the top of the table? It explains (to some extent) an excess of 32 ppmv, although my total exceeds 100% by about 50 ppmv. Art LaPella 04:37, 14 August 2007 (UTC)

[edit] Page name

Shouldn't this be at Atmosphere of Earth? - Fredrik | talk 16:42, 11 Mar 2005 (UTC)

That now re-directs here. Vsmith 16:51, 11 Mar 2005 (UTC)

[edit] Heterosphere

There's a layer in the atmosphere where the composition varies with altitude, called the heterosphere. This article divides them by temperature, so I don't know where it fits. But for example, there's an altitude (depending on solar activity) at which helium is the dominant gas. See [1]. --Andrew 06:42, Apr 2, 2005 (UTC)

I stuck it in composition. --Andrew 03:25, Apr 10, 2005 (UTC)

The strucutre of the atmosphere is generally defined in three different ways. The most common is by temperature strucutre. The other two ways is by composition (i.e. the heterosphere and homosphere) and by "function" e.g. "ozonosphere". I'll work to make this clearer in the page. --kmcolo

[edit] Early atmosphere - a merge might be in order

In case people watching this article weren't aware of it, Miller-Urey_experiment#Earth's_early_atmosphere actually has more material on Earth's early atmosphere than is present here. It might be appropriate to move some of it here and include a link over there pointing to it. Bryan 23:21, 9 Apr 2005 (UTC)

Whatever it is decided to do with these two articles, they need updating to reflect the (wonderful/beautiful imho) recent result of Tian et. al. [2] [3]. This paper was even reported on in Slashdot, it really looks like it may become a landmark in the history of ancient atmospheric science research. Urey-Miller is now fully back "in the game"! (yay! :o)--Deglr6328 02:36, 10 Apr 2005 (UTC)
Heh. I noticed this duplication between articles when I went to add information about those very results. :) I'm not an expert in the field, though, so by all means expand and improve on the material I added. Bryan 05:55, 10 Apr 2005 (UTC)
Nice research, that. I wonder how often experts considered or overlooked supersonic gas movement. One sometimes forgets the behavior of planetary-scale quantities of material. (SEWilco 18:46, 10 Apr 2005 (UTC))
  • Any links to the concepts underlying the planetary formation process which they are using? (SEWilco 18:46, 10 Apr 2005 (UTC))

The new study indicates that up to 35 percent of the early atmosphere was oxygen (200 - 250 million years ago, bubbles of early atmosphere were found in an amber).

[edit] Refractive index etc.

If this is going to be the page on the air we breathe, it should have a section on the physical properties of ground-level air: refractive index, conductivity, electrical breakdown voltage, dielectric constant, and so on.

If not, there should be a page, maybe physical properties of air with just that sort of information (as well as ground-level composition and so forth). --Andrew 03:52, Apr 29, 2005 (UTC)

[edit] Atmospheric focus

It seems that this page has what I would call an editorial slant towards those interested in the atmosphere as it pertains to space and space travel. Though indeed this is interesting it would seem to me that the page should focus on the atmosphere with a slant towards those interested in the atmosphere. This is my observation and I will be working toward that goal. Let's discuss this here so as not to step on toes that should not be stepped on. kmcolo 17:00, 31 July 2005 (UTC)

  • I think the orientation is toward the vertical levels of the atmosphere. There are separate articles for a number of processes within various layers, and you'll probably be adding a number of links to those which hadn't been connected. (SEWilco 02:15, 1 August 2005 (UTC))

[edit] Atmosphere and Gravity

I know this probably sound stupid but why dont the gas molecules in the atmosphere come fall on to the earths surface just like everyhting else. I mean they should, since they are not in orbit. Pranay ( pranay89@gmail.com )

The gas molecules do respond to the effect of gravity. Atmospheric pressure drops with increasing altitude. But gravity is a weak force, and it can only compress the atmosphere to the point where the pressure pushing molecules up (due to collisions) equals the force down. See kinetic theory of gasses. Archimerged 14:42, 15 January 2006 (UTC)

[edit] Clouds

The whole article do not mention them. TestPilotImage:Eoraptor.jpg 23:16, 22 January 2006 (UTC)

[edit] Image needs to go

In his recent edit summary, William M. Connolley said: "Density and mass - Rm the quibbles from the graph: K, not deg K, is correct, but really doesn't need mentioning. Ditto the scale: it is clear enough. Put remaining text into caption, and smallify"

However, this whole graph (Image:Atmosphere model.png) is a misleading mess:

  1. There is, of course, the "Degrees Kelvin" problem.
  2. In addition, there is an improper symbol for kilometers (Km rather than km)
  3. The use of a carat to indicate superscript in "g/cm^3" isn't pretty, but is marginally acceptable, it is understandable that software might not be able to make superscripts, but it can probably use the ³ character.
  4. But the biggest problem is that there are two independent and unrelated graphs slammed together, with the crossover point of no significance whatsowever.
  • Furthermore, the background grid is strongly and clearly logarithmic, but the scale for the temperature graph is not logarithmic. Only the graph for density is logarithmic, which in itself might warrant a clear explanation of that fact in the caption. It is just to damn confusing to justify this abomination. Gene Nygaard 01:28, 8 February 2006 (UTC) Gene Nygaard 03:12, 8 February 2006 (UTC)
I couldn't find a better one with a quick trawl, so I propose we leave it until someone finds a better one. If someone want to generate a better one they could try using the US Standard Atmosphere from here: http://www.pdas.com/m1.htm
If I get time I'll try and do it. Its probably also worth including a whole section (or subsection) on the US Standard atmosphere as it is widely used. At the moment standard atmosphere redirects to Atmospheric pressure which is misleading as that article seems to be exclusively about Earth's MSLP.--NHSavage 08:58, 8 February 2006 (UTC)

Um. I shall defned this graph (its not mine, I didn't put it there, but...). "Km" and "Degrees Kelvin" are mere typographical problems, and minor ones at that. Ditto ^. Now, as to the "unrelated" variables: well, T and P are both atmos variables. Putting them on the same graph is reasonable. Then there is a crossover, which doesn't mean anything - but so what? On this height scale, its natural to plot log P, and natural to plot plain T. Its not a great graph or anything, but it does usefully illustrate the article, and I don't understand the degree of dislike GN has for it! William M. Connolley 09:09, 8 February 2006 (UTC).

[edit] Photosynthesis

Certainly, these two sentences are not accurate: 1. "Being the first to carry out oxygenic photosynthesis, they were able to convert carbon dioxide into oxygen, playing a major role in oxygenating the atmosphere." 2. "Photosynthesizing plants would later evolve and convert more carbon dioxide into oxygen."

During oxygenic photosynthesis, the water molucule is split and the oxygen from H2O is converted into the dioxygen (O2) molecule. The carbon in carbon dioxide is converted into organic matter (call it biomass or algal/bacterial matter). Although, some carbon dioxide is respired back out of the cell as carbon dioxide, there is generally a net fixation of carbon (or net conversion of carbon dioxide to organic matter).

--216.59.253.118 20:19, 15 February 2006 (UTC)

[edit] Not GA yet

This article was nominated on Wikipedia:Good articles/Nominations, but I feel it's not yet up to the required standards as the only reference cited does not appear to be adequate for verifying all the facts in the article. Worldtraveller 00:09, 12 March 2006 (UTC)

[edit] Question

I moved the following from the article to here:

what about the exosphere?????????? that is very important. you do not state the temperature in the exosphere

It was in the subsection "Various atmospheric regions". I do not know the answer. - Liberatore(T) 12:46, 6 April 2006 (UTC)

A possible error!

I am in no position to write anything about the earth as I know very little about it's scientific properties but I think I found an error. "thermosphere: from 80–85 km to 640+ km, temperature increasing with height."

It would see to me that the thermosphere's tempature would decrease with height as it is the last layer and so close to space. Am I mistaken?

Brett

It increases with height, according to every other website I looked at including [4], [5], [6], [7] and [8]. Art LaPella 03:21, 10 July 2006 (UTC)

[edit] Two thoughts

How about some simple models - like the isothermal model - i guess kindof links in with the atmospheric pressure page???? is the air car link really worth having on this page? -deosnt really seem to link seriously with the subject. Wideofthemark

[edit] Reversion explanation

First, I reverted the unexplained change from 78% N2 and 21% O2 to 80% N2 and 19% O2, back to 78 and 21. These well-known figures can also be found in the body of the article and http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html

I also changed the percentage of CO2 by mass from .035% back to .053%. The .035% figure probably came from the NASA reference http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html , but that figure is "by volume, dry air", not by mass. I found the .053% figure at http://www.reference.com/browse/wiki/Earth's_atmosphere . Art LaPella 02:38, 1 July 2006 (UTC)

[edit] Splitting off air

I am considering splitting off the section on composition into a separate article at Air, along the lines of many (19, I believe) other wikipedias, such as de:Luft (separate from de: Erdatmosphäre. There seems to be plenty of information to make both articles substantial, and the air article could go into somewhat more detail (as the German article does). Rigadoun (talk) 17:25, 4 August 2006 (UTC)

hmmm not sure. I can see why this might be a good idea in the future but I think for the moment it would be better to just expand this section until the content is large enough to warrant a seperate page. There is also a possible overlap with Atmospheric chemistry and the links to this article would have to be carefully thought through.--NHSavage

[edit] exists"

Here's some brilliant prose from the article:

Although the atmosphere exists at heights of 1000 km and more, it is so thin as to be considered nonexistent.

—Pengo talk · contribs 14:40, 11 August 2006 (UTC)

This has to be sarcasm, but I don't understand the objection. Air molecules don't lay on the ground like water because they bounce off each other at widely varying speeds averaging about 1000 miles per hour. Most molecules bounce and fly miles above the earth, but they fall down eventually (a very few escape into space). The higher you look, the fewer molecules you find, and there is no clearcut limit. "How high is the atmosphere" is a semantic question - that is, it's about words, not about nature. The sentence looks good enough to me. How would you say it? Art LaPella 18:55, 11 August 2006 (UTC)
It was a bit inelegant. I've tried to improve.--NHSavage 20:11, 11 August 2006 (UTC)

[edit] Neutrality of this section

The sub section "The evolution of the Earth's atmosphere" needs to be marked as a theory. We all know that carbon dating is inaccurate after a few 10s of thousand years (cannot think of the exact amount right this moment...) and that anything beyond that is based on unproven theories and speculation. Therefore this must be marked as a theory to keep neutrality.

I am going to put the word theory at the top of it linked with the page on theories, if this is removed without explanation it will be because someone wishes to put this foward as fact when it is not proven and that is not neutral. If you have a valid reason as to why this should not be there please post it here before removing this edit and if it is a good reason then fine but saying "this is what happened" is not a good reason when it is unproven —Preceding unsigned comment added by Zealotii (talk • contribs) 06:20, 24 September 2006

Removed the theory link. The first paragraph of the section states:
The history of the Earth's atmosphere prior to one billion years ago is poorly understood, but the following presents a plausible sequence of events. This remains an active area of research.
Seems that is qualification enough. You seem to use the word proven in a manner that indicates a lack of understanding of how science works. Vsmith 16:46, 24 September 2006 (UTC)

"The history of the Earth's atmosphere prior to one billion years ago" is insinuating that the world has in fact existed for one billion years. Which is currently unprovable. Therefore it is stating as a fact that the world existed one billion years ago. Which is not a fact.

I suggest the opening of this sub-section be revised and changed to state at least a little more clearly that this is not a fact. —Preceding unsigned comment added by Zealotii (talk • contribs) 10:40, 24 September 2006

It's about as close to a fact as you're going to get in science, though. The scientific community's consensus is that there's overwhelming evidence for Earth being over a billion years old, the proposition that it's younger than that is an extreme minority notion that IMO doesn't warrant inclusion in every article that happens to mention Earth's age. Wikipedia:Neutral point of view#Undue weight covers this sort of thing. Bryan 23:36, 24 September 2006 (UTC)

Overwhelming evidence? Could you please at least give me links to this information as I would like to see this amazing evidence. —Preceding unsigned comment added by Zealotii (talk • contribs)

Age of the Earth and History of Earth both contain an abundance of references, for a start. Also, please sign your posts using four tildes, like this: "~~~~" — Knowledge Seeker দ 05:32, 25 September 2006 (UTC)


Dating methods used in those examples are not proof the world is that old at all. For instance, radiocarbon in carbon dating (most common dating method) decays far to fast to ever work for anything past a few thousand years and any knowlagable Evolutionist knows this. It's half-life is only 5,730 years, in other words half of it decays away every 5,730 years. After 10 half lives there is but a thousandth of it remaining, on since, things like diamonds (apparently dated to 3 billion years in some cases) still have radiocarbon on them, they are far, far younger then what is said. The problem here is far to much on wikipedia and in evolution in general is accepted as fact, when it is NOT fact and is FAR from it. The neutrality of Wikipedia is general is non existent and a lie. This site has so many unproven methods and theories and calls them fact, or just accepts them as true. I request that entire section be either tagged obviously as theory or removed entirely.

Sorry I took so long to reply, I had things that needed doing. "Zealotii 09:34, 15 October 2006 (UTC)"

My theory tag removed again? Why are people having such a hard time with something so simple? The only reason there are so many people that accept this kind of thing is because they assume it be to true as evolutionists seem to take great delight in tagging their documents as fact. "Zealotii 09:51, 15 October 2006 (UTC)"

Please stop wasting everyones time, including your own. If you want to debate evolution, go to an internet newsgroup. Quite why you think this stuff depends on radiocarbon dating I don't know... William M. Connolley 10:53, 15 October 2006 (UTC)

That was an example of many, my point was if it depends on ANY dating method "theory" we have now it is incorrect. I am not here to debate anything, you are preventing neutrality by not allowing a theory tag ON WHAT IS DAMNED WELL THEORY. If you were NEUTRAL you would not be here debating this with me. The truth is the truth. I am not here to debate anything. Only to correct what is being displayed as fact to theory, to prevent more wide spread and outrageous ignorance on the subject. "Zealotii 11:14, 15 October 2006 (UTC)"

Look, I will simply say this.

It IS a theory. You know this as well as I. Therefore I am CONTRIBUTING by FIXING an error which states it as fact which is INCORRECT.

There is no way to argue this save you want it removed because you want your views on this section and not the neutral truth, you want it to lean towards evolution. "Zealotii 11:18, 15 October 2006 (UTC)"

If you want to discuss evolution, do it over there or better still at the appropriate newsgroup. Everything we "know" about the world is either superstition or theory. Much of it is accepted as "fact" and under any legal system I'm aware of - as the "theory" of gravity, which you ignore at your peril, or the "theory" of optics that you implicitely use whenever you think you see something first hand. The approximate age of the Earth (give or take a few million years) is not under any serious debate. --Stephan Schulz 11:30, 15 October 2006 (UTC)

...

Those examples are irrelevant. We can see them working everyday all day and it would only be named a theory because we may not fully understand it yet. But it is still there. This, on the other hand, has nothing to go by at all save disproven dating methods. The age of the earth is always under serious debate if you had not noticed since it is a key factor in evolution, which itself is always under serious debate. "Zealotii 11:47, 15 October 2006 (UTC)"

Sorry to break it to you, but evolution is also not under serious debate among educated people. And even if it where, the age of the Earth is independent of evolution. Earth is known to be ancient (as in "billions of years old") by a number of independent and reinforcing dating processes, none of which is radiocarbon dating (which, btw. is not "disproved" either). But this discussion is off-topic here. Go to Age of the Earth if you must, but be prepared to back anything you claim up with reliable sources.--Stephan Schulz 15:03, 15 October 2006 (UTC)

No, there is no evidence or actual proven working methods. The problem with science these days is it is not science. It is people trying to prove one certain thing. Please show me reliable sources for your arguement with proof. Also, no, radiocarbon dating is flawed and any respected evolutionist scientist will tell you this. There is however, "evidence" that goes along like this: (direct quote from [9] READ THE SOURCES THIS INFORMATION IS FROM)"While it is common to cite verified predictions as ‘proof’ of a scientific law, this commits a basic logical fallacy called affirming the consequent.

1) Theory T predicts observation O; 2) O is observed; T is true.

 To see why this does not follow, consider:

1) If I had just eaten a whole pizza, I would feel very full; 2) I feel very full; I have just eaten a whole pizza.

Finding certain things in substances does not mean the actual theories are correct. All evolutionist evidence thus far is inconclusive, based on this or assumptions/unproven hypothesis. Again, if you have this evidence please show it as I would love to see it. But if you are just one of those people that assume things to be true because they release millions of new theorys about the same thing so often, that it somehow becomes truth as they never decide to show it otherwise, please rethink your comment. "Zealotii 04:50, 18 October 2006 (UTC)"

Once again, if you would teach us benighted ones the world isn't a billion years old, the place to start is at Talk:Age of the Earth - it's off-topic here until you can show us the light there. If you aren't impressed by Wikipedian policy and habits, then call it Christian deference to those placed in authority over you, or something. Art LaPella 06:41, 18 October 2006 (UTC)
Agreed with Art. I'll put Talk:Age of the Earth on my watchlist. If you want to discuss these issues, go there (although it likely is still off-topic to a certain degree). Please first read something like the talkorigins age of the earth FAQ to understand the currently used dating methods and arguments for an old earth.--Stephan Schulz 13:35, 18 October 2006 (UTC)

Again I am sorry for taking so long to reply, there were things that required my attention... I think I will go there and discuss these things further. I am well aware of the dating methods used and the current most popular, given its amazing half-life, radiometric dating (decay rate of isotopes). I also have many reasons why it is unrealiable and in some cases can help to show the oposite... But as you requested I shall not post such things here anymore. "Zealotii 10:06, 19 October 2006 (UTC)"

You are talking past each other because of a basic misunderstanding and imprecision in the use of words such as theory, fact, and truth. The very best that science can do is to establish a well-substantiated theory. Theories may always be improved, but never proven. Science pursues truth, but we can never know whether it has been reached. A fact is not the opposite of a theory, and truth and fact are not synonymous. Proofs belong in the disciplines of mathematics and logic which of course are helpful to scientists as they make observations (gather facts), formulate hypotheses, test those ideas, and develop theories to explain what they observe--and the process continues. The moment someone tells you that a scientific theory has been proven, you should be extremely skeptical. History is replete with theories "proven" and then later found to be incomplete, or flat wrong! There are various theories about the evolution of the Earth's atmosphere. Some of them are pretty well substantiated by scientific evidence. Science is a human enterprise. I leave truth to the realm of God. Norm 21:29, 15 April 2007 (UTC)

A better argument would be to mention that for rocks more than several thousand years old, Potassium-Argon dating is used. Check out this link. Zealotii is correct, carbon dating is not useful in this time range. Good thing is, we have other ways to date old material. One must remember that as precise as science seems at any given moment, few things are completely proven...hence the idea of theorems. Wikipedia also is against the idea of "weasel wording", so items sometimes have to be stated as complete fact, even if they aren't. All they need to fit is the current consensus argument, regardless of apparent truth. Thegreatdr (talk) 17:32, 8 January 2008 (UTC)

[edit] errors on page

This paragraph has errors: During the next few million years, water vapor condensed to form rain and oceans, which began to dissolve carbon dioxide. Approximately 50% of the carbon dioxide would be absorbed into the oceans. One of the earliest types of bacteria were the cyanobacteria. Fossil evidence indicates that these bacteria existed approximately 3.3 billion years ago and were the first oxygen-producing evolving phototropic organisms. They were responsible for the initial conversion of the earth's atmosphere from an anoxic state to an oxic state (that is, from a state without oxygen to a state with oxygen). Being the first to carry out oxygenic photosynthesis, they were able to convert carbon dioxide into oxygen, playing a major role in oxygenating the atmosphere.


1) First, there is no definitive evidence nor consensus that photosynthizing cyannobacteria were present on earth at 3.3 bya, though some scientists argue this. 2.6 ba or earlier is the scientifically safe statement -- see recent paper in nature, and tis references:

[[10]]

2) The paragraph fails to convey what we do and do not know about precambrian oxygen levels. See the same reference above as well as Goldblatt [[11]] This is not my field, and I'm working on another project of interest to me. Is there an earth scientist/ paleoecologist to look into this? I can supply a list of other pertinent references. Loco 00:01, 18 October 2006 (UTC)

Simple question.Why humans can see sky in a blue color.

—Preceding unsigned comment added by 81.132.165.246 (talk • contribs) 18:44, 20 December 2006

[edit] Thickness of atmosphere. Could this actualized set of data be changed in the page?

Where it says:

However:

  • 57.8% of the atmosphere by mass is below the summit of Mount Everest.
  • 72% of the atmosphere by mass is below the common cruising altitude of commercial airliners (about 10000 m or 33000 ft).
  • 99.99999% of the atmosphere by mass is below the highest X-15 plane flight on August 22, 1963, which reached an altitude of 354,300 ft or 108 km.

Therefore, most of the atmosphere (99.9999%) by mass is below 100 km, although in the rarefied region above this there are auroras and other atmospheric effects.

Should say:

However:

  • 68.054% of the atmosphere by mass is below the summit of Mount Everest.
  • 73.004% of the atmosphere by mass is below the common cruising altitude of commercial airliners (about 10000 m or 33000 ft).
  • 99,000 072% is below 31200 m.
  • 99,901 189% is below 48200 m.
  • 99,990 117% is below 65100 m.
  • 99,999 006% is below 79800 m.
  • 99,999 901% is below 92900 m.
  • 99,999 991% of the atmosphere by mass is below the highest X-15 plane flight on August 22, 1963, which reached an altitude of 354,300 ft or 108 km.

Therefore, most of the atmosphere (99,999 970%) by mass is below 100 km, although in the rarefied region above this there are auroras and other atmospheric effects. —The preceding unsigned comment was added by JustToHelp (talk • contribs) 19:50, 13 January 2007 (UTC).

Just changed the unsourced numbers to published figures from a standard text. The above calculations by User:JustToHelp would appear to have WP:OR problems as he states the numbers were derived by spreadsheet calculations. Sourced published figures are preferred. Vsmith 20:14, 13 January 2007 (UTC)

Reverted JustToHelp's OR calculations again. This time he inserted them following the citation I had given for the tabulated data, thereby making it seem as though his numbers were cited. His values - calculated to six decimal places are quite absurd as the uncertainties of the data would make such precision meaningless. Let's stick with published values and forego the OR calculations. Vsmith 23:34, 15 January 2007 (UTC)

Would you please take a look to NRLMSISE-00 and/or so we can start talking about facts.

You say that 6 decimal numbers are absurd, then: why is there a 99.99997% number accepted?.
Look, I have had in the past a difficult time triyng to understand how thick the atmosphere was. There should be a limit we can accept as "enough". I looked to a lot of pages on internet and always there was no clear answer to this "perceived" limit. Then I discovered that I could help other to find a fast awnswer by posting at wikipedia. So, i downloaded all the nedded data from NRLMSISE-00 and built an "acceptable" answer to all. Then to help others I posted my findings on this page, more than a year ago. Do you think that it is needed to force others to calculate an awnswer because you dislike what I have posted?
Now that section just got changed and the verion you want to IMPOSE is not the best it could be IMHO. So i tried several times to improve, and the only awnswer you see fit is: ERASE ALL, IT'S NOSENSE. Do you think that it is needed to force others to calculate an awnswer because you dislike what I have posted?
Why dont look at the data and not your opinion that this is OR and MUST be erased. Do the data presented contradict the information you wnat to belive? Is wrong to try to improve on what is presented? Pleased DO READ the facts not opinions. If you dislike the form, not the facts, please help to correct. The facts, either you like them or not would persist and be there. Your opinions will change with time. JustToHelp 05:03, 16 January 2007 (UTC)

OK, I looked at NRLMSISE-00. There should not be a limit on how high is enough - JustToHelp's own graph shows the air fades away gradually with no sharp limit. 99.99997% isn't a 6 decimal estimate if you think of it as the complement of 0.00003%, with 1 significant figure. JustToHelp's 73.004%, for instance, has 5 significant figures and a fraction of a degree temperature difference would be enough to make it wrong. The issue isn't whether to force others to calculate the figures - the issue is two competing sets of figures. Vsmith has provided documented figures, not his own calculations. JustToHelp's figures apparently come from [12], a website that provides calculations, but the underlying formulas aren't reviewed the same way as a scientific paper is. If JustToHelp addresses the problems above, the real scientists (that is, not me) will, um, have more time for him. Art LaPella 06:07, 16 January 2007 (UTC)
If I might chime in, the comment about 99.99997 being really one sig figure, is spot-on. Art's right. SBHarris 00:04, 22 January 2007 (UTC)

[edit] Earth's atmosphere. Wrong percentages?

The first paragraph says: It contains roughly 78% nitrogen, 21.12% oxygen, 0.93% argon ... These percentages sum up to more than 100%. It just seems wrong.

I suggest they should be changed them to: 78% nitrogen, 21% oxygen, 0.93% argon.

Also table on the right hand side, showing Nitrogen 75% seems incorrect. —The preceding unsigned comment was added by Cgeorges (talk • contribs) 18:58, 17 April 2007 (UTC).

Part of the confusion is that nitrogen is either 78% or 75% depending on whether you include water vapor and other variable components. A case can be made for measuring percentages of the non-variable (well, at least not so variable) components of the air only, so that the answers don't depend on humidity - there's more water vapor over the Amazon than over the Sahara, therefore there is a larger percentage of nitrogen etc. over the Sahara, just because the water vapor is gone. Also, a total including "roughly 78%" can add to more than 100% due to round off error. But I basically agree with Cgeorges that the confusion should be cleared up. Art LaPella 21:32, 17 April 2007 (UTC)
Please, someone who has knowledge/access to better references, PLEASE change the %s to add up to 100% in any manner that makes sense (e.g., include various ranges of %s for each component so that they at least COULD add up to 100%). Thanks!! philiptdotcom 03:17, 5 November 2007 (UTC)

[edit] Observational Database?

A large observational database of many different atmospheric constituents from a host of platforms including UARS is available. This was created as part of ESA Envisat and NASA Aura validation. It is of general use. Do you think it should be added to the article text?

[edit] Density and Mass

Has anyone noticed that according to the graph "NRLMSISE-00 standard atmosphere model" the temperature RISES beyond 80km altitude to reach an amazing 460 degrees Celsius (!) in 150km altitude. Can the people who posted this graph perhaps look into this again and correct this nonsense? —The preceding unsigned comment was added by 218.186.9.5 (talk) 09:05, 2 March 2007 (UTC).

The thermosphere article (and anything else I've read) agree that the temperature rises beyond 80 km: "Thermospheric temperatures increase with altitude...Temperatures are highly dependent on solar activity, and can rise to 2,000°C." Art LaPella 18:16, 2 March 2007 (UTC)
Yep. Don't confuse temperature with heat. It's very hot but there's not much of it, so it won't burn you. Think of the solar corona at millions of degrees. Such temperature inversions, with "vacuum" between to insulate them from conduction and convection, are possible. SBHarris 19:49, 2 March 2007 (UTC)

[edit] Composition

According to the Nasa Water Vapour Project reported at http://www.engr.colostate.edu/~ramirez/ce_old/classes/ce422_ramirez/CE422_Web/WaterVapor/water_vapor_CE322.htm the average precipitatable column of water over the globe varies from 22 to 27.5 mm. This converts to 0.34 to 0.43% water in the atmosphere by volume or 0.21 to 0.27 % by mass.

The mass concentration given for carbon dioxide is in error. Carbon dioxide being 51% denser than air must make it greater by mass composition than by volume. A straight molecular weight calculation (ignoring deviation from ideal gas) gives a result of 0.058 % carbon dioxide by mass. It is not clear to me that laboratories take into account the deviation from ideal gas when calculating carbon dioxide concentrations by volume.

Errors in calculating the mass of carbon dioxide in the atmosphere give rise to the frequently quoted statistic that only 50% of human emmissions are retained in the atmosphere. The true figure over the last 40 years exceeds 60% and has exceeded 100% in some years.

Chris Seymour 05:58, 20 March 2007 (UTC)

How can retention exceed 100%? Ottoump 16:50, 24 July 2007 (UTC)

[edit] Average temperature

Are there any sources to establish that the average temperature at the surface is 15 C? I looked and every source I saw gave the number that used to be in this article, 14. If no one can cite a source for this, I will change it back. Mr.Z-mantalk¢ 06:30, 29 May 2007 (UTC)

[edit] Troposphere=

Many textbooks state that the reason that a rising air mass cools is because of the Joule Thompson effect. This is not correct. The JT effect can only account for 0.5 K of cooling in air originally at 1 bar and 300 K. The correct explanation is that a rising air mass does work adiabatically upon the surroundings, so its internal energy, hence temperature, decreases. This is the explanation for my edit of that paragraph. Dr Thermo 01:54, 6 June 2007 (UTC)

[edit] Troposphere 2

I appreciate the recent edit regarding the temperature profile in the thermosphere. I think I will stick to my guns regarding the reason for temperature drop. I changed the explanation from the Joule Thompson effect to work against the surroundings. Another editor changed this to work against gravity. I don't think this is correct. The air mass rises because of bouyancy. It takes energy to sink a bouyant body. The air mass expands as it rises becasue of lower pressure at higher altitude. When it expands, it does work by pushing back the surrounding air. The amount of work is given by w = -integral(pdV), negative because energy goes out, p is the pressure of the surrounding air, and V is the volume of the air mass. Before I edit, I will await comment here. Dr Thermo 20:15, 6 June 2007 (UTC)

Yes, of course you are correct about the basic reason for the adiabatic temp lapse. For a really good intro article which starts simple and goes into detail, see: [13], plus the link to hydrostatic equilibrium constraints. Of course, the gravitational gradient determines these lapse rates and the stable structures. In theory there need be no temperature lapse rate at all if a fluid packet does no PdV work on the way up or down, or else such work is compensated by heat input or radiation (non-adiabatic systems). But even for isothermal atmospheres, there must be hydrostatic equilibrium, and in that case different potentials in a field gravity, mg*dh, show up as differing VdP potentials in fluid packets at different h heights. No work is done here, but mg dh potentials and VdP potentials have to match, with altitude. The simplest of these relations is with ordinary incompressible fluids where PV = mgh or P = rho*g*h. But one needs this structure in gases also, to make sure that the pressure differences on each parcel of fluid (from top to bottom) are enough to keep them suspended (equal their weight), and that the pressure at any point equals the integral of all weights above it. So in the simplest ideal gas case you wind up with things like mg(dh) = nRT dP/P, which already gives you the approximate exponential pressure structure of our lower atmosphere. The article above has corrections for semi-adiabatic cases where thermal structures are semi-stable (don't change much over altitudes of interest), but still satisfy the hydrodynamic equilibrium equations everywhere, as they always must. SBHarris 00:35, 25 July 2007 (UTC)

The observations I make here are concerned with the global aspects of air pressure/temperature and do not take into account water content. Water content is a local matter, it is very variable from one location to another. Air pressure is fixed by gravity and atmospheric mass so it forms the true basis for analysing global effects. Water content effects are thus played out against a pressure profile defined by a background of dry air pressure.

I am not satisfied with this statement "When an air mass rises the pressure upon it decreases so it expands, doing work against the opposing pressure of the surrounding air"

The pressure gradient is along the gravity gradient, in effect vertical; if the expanding air was doing work against the "opposing pressure of the surrounding air" it would have to produce a movement tangential to the surface which would in turn cause a tangential pressure gradient against this movement. The net result should be a local increase in height appropriate to the increased energy in the parcel whereby some of the kinetic heat energy is transformed into gravitational potential energy, cooling the gas. Not all the heat energy is converted into potential energy, the heated air parcel will always be warmer than its surroundings and will rise steadily until thermal effects disappear due to the reduction of pressure at the top of the troposphere. This is of course the mechanism that drives the atmospheric circulation with its hadley, ferrel and polar cells.

I understand that the role of gravitational energy in the vertical temperature profile was proposed in a previous edit. I have looked but cannot find it, would someone be so kind as to indicate the relevant edit?. The role of gravity is central to the atmosphere, it is after all gravity that keeps it on the earth so it is entirely necessary that gravitational effects are included at every stage. Damorbel (talk) 19:59, 19 December 2007 (UTC)

[edit] Oxygen - air confusion

Shouldn't there be a part of this article about the common confusion between air being oxygen, even though it's obviously not? Because there are definately some people out there who believe air = oxygen, and need to be proven wrong so they can get it right in the future.

Needs to be done IMO.

[edit] Evoluton on Earth Section, Oxygen production error

The Evoluton on Earth Section states that Cyanobacteria "... were able to convert carbon dioxide into oxygen[,]" and "Photosynthesising plants would later evolve and convert more carbon dioxide into oxygen." This is an incorrect representation of photosynthesis. Oxygenic Photosynthetic life captures carbon dioxide in organic molecules used for energy storage and tissue construction in a process independent of the light reactions which splits water into gaseous oxygen and hydrogen ions. I've adjusted the passage to correctly reflect this, stating now that "[Cyanobacteria] were able to convert water into oxygen while sequestering carbon dioxide in organic molecules[,]" and "Photosynthesising plants would later evolve and continue releasing oxygen and sequestering carbon dioxide[.]" user:Anonymous 20 June 2007

[edit] 100%

"This is complete nonsens[sic] , because the first four compounds make more than 100%" I didn't write those words and they need more Wikipedia:Civility, but "Looks like someone can't add" isn't civil either, especially since he can add. 78.084% N2 + 20.946% O2 + 0.9340% Ar + 0.0383% CO2 equals 100.0023%. There is indeed an apparent error. Art LaPella 20:55, 26 June 2007 (UTC)

The numbers match the NASA source used in the text, so it is apparently an externally originating problem. Dragons flight 01:19, 27 June 2007 (UTC)
Please, someone who has knowledge/access to better references, PLEASE change the %s to add up to 100% in any manner that makes sense (e.g., include various ranges of %s for each component so that they at least COULD add up to 100%). Thanks!! philiptdotcom 03:18, 5 November 2007 (UTC)
I would like to see some small explaining text below the table saying e.g. that these are the official composition figures from NASA or something similar. Thanks 130.238.197.149 (talk) 16:18, 8 February 2008 (UTC) (sv: Beryllium-9?)

[edit] Citation-request partial answer (std temperature)

I saw a line marked Citation Needed, "The average temperature of the atmosphere at the surface of Earth is 15 °C (59 °F).[citation needed]", and believe that I have a partial answer. As a pilot, we were taught to base all calculations off of the "Standard Temperature and Pressure", which is 15°C and 29.92"Hg at sea level. For all variations from that (i.e., higher altitude, warmer or cooler temp, higher or lower barametric pressure), one applied a formula (or consuted a table) to get adjusted factors for doing calculations such as true airspeed or density altitude.

I don't know if 15°C is the "average" temperature of the Earth's surface, but it is the "Standard Temperature" used by pilots and meteorologists as the basis for calculation. I'm sorry, I don't have a citation for this handy, although I suspect it's an easy Google search (which I would do, but I'm running late, right now.) I am aware (but also without citation) that there is an "alternate STP" based on an air temp of 0°C and some other pressure at sea level, but it is my understanding that this is to simplify the tables/calculations, rather than representational of real-world conditions.

I hope that's useful to someone looking to create a cite for that statement. Oliepedia 15:15, 13 August 2007 (UTC)

[edit] Picture Incorrect

I've notices that in the article a picture of the atmosphere showing the sections is missing one, it is missing the ionosphere which is between the mesasphere and the thermosphere. this could cause some confusion to people researching the subject. —Preceding unsigned comment added by 220.238.188.88 (talk • contribs) 10:19, 16 August 2007

Please see ionosphere for the relationship between it and the atmospheric layers. It is not between the other zones - rather an overlapping relationship. Vsmith 11:13, 16 August 2007 (UTC)

[edit] Variation in the thickness of Earth's atmosphere

Mountaineers are interested to know more about the variation in barometric pressure due to the varying thickness of the Earth's atmosphere. I think this thickness variation is due to centrifugal force effects of the Earth's rotation.

Specifically, mountaineers would like to know:

What is the variation in sea level barometric pressure between the pressure at the equator and:
a)10 deg latitude
b)20 deg latitude
c)30 deg latitude
d)40 deg latitude
e)50 deg latitude
f)60 deg latitude
g)70 deg latitude
h)80 deg latitude
i)90 deg latitude

DO ANY OF THE BAROMETRIC PRESSURE EQUATIONS TAKE LATITUDE INTO ACCOUNT?
Would the variation be about the same for the northern versus southern latitudes?


These pressure differences are related to items of interest to mountaineers such as:

Is the air less dense at the summit of Denali (20,320') than on Aconcagua (22,841') due to the higher latitude?

Chimborazo(20,000'+)is on the Equator in Ecuador. Thus it sits on the "bulge" caused by the Earth's rotation and is said to be the summit farthest from the center of the earth. Which effect is greater on the density of the atmosphere on Chimborazo: the "height" due to the bulge, or the greater thickness of the atmosphere at the Equator? In other words, would the air on Chimborazo be less dense if it were located at higher latitude?

On a high summit, say 20,000', would the air be more dense on a cold day or a warm day? (It would seem that if it were warm, the atmosphere would expand and more air would be above you so the pressure would be greater. Conversely it would seem that on a cold day, the air would be dense and would contract, thus more of the total atmosphere would be below your 20,000' location and so the pressure would be less at your 20,000' location.)


Can someone add more info on this topic to the main article? Ice axe 2 02:22, 30 August 2007 (UTC)--Ice axe 2 02:22, 30 August 2007 (UTC)

[14] and [15] confirm that effect, but don't quantify it. Art LaPella 00:10, 31 August 2007 (UTC)

Ah ha! I found some data on page 8-8 in the 19th edition of Cameron Hydraulic Data by Flowserve. It has a table for Correction of Mercurial Barometer for Latitude in Inches Hg to Reduce to 45 deg Latitude. 71.111.55.34 22:50, 15 September 2007 (UTC)

[edit] Noinclude

This edit introduced the stray word "noinclude" near the bottom of the article. I don't know why it's in Template:Atmospheres. Art LaPella 02:15, 3 September 2007 (UTC)

Resolved. Art LaPella 00:09, 4 September 2007 (UTC)

[edit] Conflicting atmospheric mass figures

Earth's atmosphere#Pressure and thickness now says "total atmospheric mass is 5.1361×10^18 kg [16]." But Earth's atmosphere#Density and mass still says "According to the National Center for Atmospheric Research, 'The total mean mass of the atmosphere is 5.1480×1018 kg with an annual range due to water vapor of 1.2 or 1.5×1015 kg...'". Art LaPella 00:09, 4 September 2007 (UTC)

Good catch. The 5.1361 number came from a 1988 paper, the 5.1480 number from a 2005 paper (with some overlap of authors). About a .23% increase. I've updated the article accordingly. --Vaughan Pratt (talk) 07:17, 30 May 2008 (UTC)

Thank you. Art LaPella (talk) 02:04, 31 May 2008 (UTC)

[edit] Merge Proposal

The page Air used to redirect here but someone recently changed it to be its own (stub) article. Why was this page not just left as a redirect? The Earth's atmosphere article is quite good. I propose we remerge them.Jyuichi 05:25, 7 September 2007 (UTC)

I think you're right. I've been bold and just done it. There was nothing to merge as far as i could see William M. Connolley 10:07, 7 September 2007 (UTC)
What I was going to do was translate de:Luft, which is a good article. I think there is a place in Wikipedia for an article about air.- Gilliam 05:35, 9 September 2007 (UTC)
I understand what you are trying to do but air is essentially defined as "the earth's atmosphere" so it might be better to incorporate the information from de:Luft in to this article, see Wikipedia:Translation. Jyuichi 23:43, 9 September 2007 (UTC)
I think it's a mistake to redirect Air to Earth's atmosphere. I understand that the historical reason for it, but conceptually they should be fairly different articles, even though they cover a lot of common ground (i.e., air is what we breathe and so is Earth's atmosphere). Air should probably reflect more about the history of our understanding of the stuff we breathe as well as our cultural constructs around it (association with earth/fire/water, association with wind, association with the sky, spirits, etc.). This article, on the other hand should focus more (as it does) on the chemical/physical properties of our atmosphere, how it relates to life on earth, how it has changed over the course of our planet's history, and how it compares to other planets. It's kind of strange that we are one of the only major wikipedias not to have an article on Air. (The German wikipedia is not the only one to have separate articles for air and Earth's atmosphere. So do the French, Spanish, Italian, Japanese, Chinese, Russian, and Portuguese Wikipedias, among others. (The Korean Wikipedia, on the other hand, follows our model).
If we don't want to have separate articles for them, we should probably move this one to Air, the much better-known name for this topic. After all, Sun is Sun and not Earth's star. Jun-Dai (talk) 18:21, 14 March 2008 (UTC)

[edit] Temperature Mesosphere

It says in the article that the temperature of the Mesosphere increases with the height. I assume it should state decreases? BillHicksRulez 00:29, 27 September 2007 (UTC)

I agree. After consulting the graph at Earth's atmosphere#Density and mass, Mesosphere, and its reference, I changed "increasing" to "decreasing". Art LaPella 02:01, 27 September 2007 (UTC)

[edit] The Noble gasses

The page on the Noble gasses says 'Eventually all the known noble gases except for helium were discovered in the air'

Then how Radon is not in the chart. —Preceding unsigned comment added by 86.143.7.146 (talk) 07:50, 27 September 2007 (UTC)

[edit] 101,00483 percent ??

if you add up all the percentages from the table at the right, you get 101,00483 percent. That does not make any sense :b q: Crakkpot (talk) 20:36, 18 February 2008 (UTC)

It's probably got something to do with how it say's the air is about 1% water vapor. Although granted, 101.004883% is more than 1% over 100, so the exact percentage of water vapor would actually have to be -0.00483% in order to add up to exactly 100.--Foot Dragoon (talk) 01:47, 19 February 2008 (UTC)

[edit] Carbon Dioxide and parts per million

How many parts per million does carbon dioxide need to gain to cause an increase in percentage? What i mean is, what is the relationship between percent of atmospheric gas content, and parts per million? would say, 1000 ppm be 0.01% of the atmosphere? RingtailedFox • Talk • Contribs 03:24, 2 March 2008 (UTC)

If you're comparing apples to apples (that is, not confusing percent by mass with percent by volume), then your question is about arithmetic. Percent means parts per hundred, so 1000 ppm (parts per million) is 1000 millionths, or 1 thousandth, or 1 tenth of a hundredth, or 0.1% (not 0.01%). Art LaPella (talk) 05:34, 2 March 2008 (UTC)
Yes, i am trying to compare apples to apples, as you said. I understand percent as parts per hundred (pph). thanks for clarifying things for me :) RingtailedFox • Talk • Contribs 18:26, 2 March 2008 (UTC)

[edit] Average air mass and pressure

Both the mass of the atmosphere (5148.0 teratonnes) and the area of the earth (51007.2 megahectares) are known to impressively high accuracy, from which we can deduce the average mass (not to be confused with weight) of air over a square meter of the earth's surface equally precisely as 10.093 metric tonnes, which I've just now pointed out in the article. However this has got me to worrying about how this is reconciled with the standard atmospheric pressure of 101.3 kPa. The assumption of a constant gravitational force of 9.78 N/kg at all altitudes should give an average pressure of 98.71 kPa, 2.5% below the standard, and even lower when one factors in lower gravity and higher centrifugal force at higher altitudes. The only explanation I could come up with is that centrifugal force also tends to push the atmosphere away from the poles to the equator, creating enough variability to make a 2.5% discrepancy part of the overall noise. Is that the explanation, or is there something else going on here? --Vaughan Pratt (talk) 07:00, 30 May 2008 (UTC)

Standard atmospheric pressure is an historical convention chosen by mid-latitude scientists to represent typical sea level pressure. I'm not at all surprised that it does not represent an actual average of the pressure over the surface of the Earth. Dragons flight (talk) 02:47, 31 May 2008 (UTC)
Well I'm surprised. I'd be ok if it were off by a fraction of a percent, but 2.5% seems excessive. I worried about this for a while until it dawned on me that the land above sea level was displacing sufficient air to raise the atmosphere significantly. Using a commonly cited estimate of 840 m for the mean elevation of the earth's land mass (which I assume is defined as the volume of land above sea level divided by the Earth's land area of 148.9 Mm²), the air so displaced comes to .125 Mm³, or 138 teratonnes based on a mean density of air of 1.1 kg/m³ at a mean altitude of 420 m. Redoing the math assuming 5148+138 = 5286 megatonnes of air gives 101.3 kPa, right on the nose! The 98.71 kPa figure should thus correspond closely to the atmospheric pressure at the mean elevation above sea level of the bottom of the atmosphere, rather less than 840 m when the area of the oceans is factored in, namely 840*148.9/510.07 = 245 m. (I was also bothered by the contributions of the earth's oblateness and centrifugal force, but it seems reasonable to assume these cancel exactly on the assumption that centrifugal force bulges the earth and the atmosphere out to the same degree.) --Vaughan Pratt (talk) 05:40, 5 June 2008 (UTC)