The science article that is referenced is actually interesting and I'm glad you provided me with a pointer to the idea, itself. Normally, in publications about greenhouse gases here on Earth you will find that O? and N? are not listed as having important effects because they are "vibrationally challenged" molecules. See, for example, the first link below where it says,
? ? "Both O? and N?, the most abundant gases in the atmosphere, are
? ? symmetric molecules, made of two identical atoms whose electric fields
? ? just cancel each other out. Neither atom can hold the electrons any more
? ? tightly than the other, so there is no difference between the electrical
? ? field on one side of the molecule versus the other. The symmetry is
? ? unbroken when you stretch or compress the bond. Symmetrical
? ? molecules with only two atoms are never greenhouse gases."
Note the use of "never" in that chapter. The symmetry idea makes a lot of sense, by the way. There is no oscillating dipole.
N? and O? do not have the bending modes found in, for example, CO?. The energy equipartition law (applies to large number population statistics) is pretty accurate about how energy distributes into these various modes. However, isotopic differences (one isotope matched with a different one) may lead to weak effect. But probably not in the bands that matter on Earth. I'm mostly curious about N? and O? acting as foreign molecules involved in broadening of other greenhouse gases, now that this subject has been brought up.
I have generally accepted the conclusions offered by those studying all of the pressure-broading effects and the net "take" on all this. In short, I've accepted the opinion offered in the above quote without digging more into the intimate details. But this is a good time to learn something, I think.
Not the web page you chose to cite, but the underlying paper it hints towards (see 2nd link below) is actually pretty interesting. It's a highly simplified 1D model. And it involves a different solar flux, as well. And the peak values you mention are only in the case where most of the atmosphere is CO? (which is nothing like our current atmosphere) and also where these pressures are quite high (and unlikely besides.) It also focuses only on wavelengths of λ ≈ 4.3μm (collision induced) and λ > 20μm (rotational) and pressure-broadening at very high presumed pressures. So the circumstances of the paper are significantly different from here on Earth, today.
How might that apply to Earth, today, with the current sun? I don't exactly know. But it's interesting to investigate the details of pressure-broadening related to N? and O?, whether self- or foreign- in effect. So I will. It should be helpful to my own understanding. And I will, of course, write to specialists in the area to get their additional help. That takes time and no one here will care. But I'm just pointing out that I'm glad for the pointer. So thanks.
I don't know if you know, but Rasool & Schneider in 1971 also used a simplified 1D model about atmospheric CO? on modern Earth and came entirely to the wrong conclusion. They were corrected on at least four points within the following year, including a couple of fatal flaws they themselves found and reported that others missed. By 1972, their conclusions were dead. But the paper remains significant because it made a good attempt at producing quantities that helped to bring out more ideas that needed to be dealt with AND because they also separately discussed the effects of aerosols, which was important to bring into the mix.
The point here is that you MUST delve deeper into things if you are going to question the comprehensively informed opinions of researchers who do specialize in these areas and know the details well. And an additional point is that it takes time even for these informed opinions to settle and for a consensus to evolve. You cannot just pick something out of the blue, especially something like this article. This article is (1) discussing Mars, and (2) is examining "the atmospheric implications of high N? partial pressures on the climate of early Mars [which] have not been investigated so far." Note that this is a "first paper" of sorts. It is by no means a settled consensus opinion. There is quite a difference.
The paper mentioned above references another important paper. See 3rd link below. I've written to the lead author of that paper, because it provides important information needed to interpret the paper in the 2nd link as it may relate to the early Earth. How these things propagate into the situation of the modern Earth atmosphere is still another thing to study. I'm sure that in the end I will come back around to finding exactly what I quoted at the outset. But with some improved mental "nuances" added.
EDIT: Colin Goldblatt just sent me a copy of his Nov. 2009 paper. Very quickly and much appreciated. I'm currently of the mind that this is about foreign broadening effects, but I'm not yet sure. If it is about self-broadening, I'm going to learn something here. Otherwise, not so much. I've written and asked this question.
The problem is that you're comparing earth to mars, which has no magnetic field, much lower gravity, no more core heat, and no atmosphere of any kind. It's clearly true that there's a difference. However, one could just as easily blame the difference in the lack of core heat, and the mass of the planet, than on the lack of oxygen and nitrogen in the atmosphere.
On the other hand, since I see you're posting WUWT, I think it safe to assume that scientific credibility isn't at the top of your list.
Gee, I wonder why someone like "Goddard" would use a pseudo name?
I don't know the answer but Goddard has an interesting discussion here in a related matter
http://wattsupwiththat.com/2010/05/08/ve...
Note: I would be really surprised if Pegminer agreed with ChemFlunky, that the temperature of the planet with nitrogen would be same as the temp of the planet without an atmosphere but I would also be surprised (pleasantly), if he would kindkly refute it.
At the moment, I can't get to the linked article on warming due to pressure broadened nitrogen. It does sound interesting but I can't really comment on it without reading it.
If we neglect this effect (for now) then I would expect that very little of the warming is due to the nitrogen and oxygen. You would really want to run a climate model to get the details right, but it's hard for me to see how the non-greenhouse gases are going to heat the planet. Sunlight comes in, heats the planet to its radiative equilibrium temperature, and the planet radiates back into space. Radiation operates much faster than convection or conduction, so I believe it would completely dominate the situation. Without the downward longwave radiation, how is the surface of the planet supposed to get any hotter than it would be with no atmosphere at all? I think the sunlit side will get quite hot, and the night side will be very cold (kind of like the moon), however there will be enough convection to keep things a bit more equable on Earth than they are on the moon.
Here's an interesting observational experiment people can try some partly cloudy and cold night. When I was growing up in Southern California, I would hope (in vain) that we might get a little snow where I lived. Here was the situation: a cold front goes through, and the post-frontal air still has a few instability showers, but it is cold, and if it's nighttime and clear, then the temperature could easily fall below freezing. I thought that if the temperature dropped so that it was below freezing, then if one of the showers drifted over then voila! we would have snow. I kept going outside and checking my thermometer, and sure enough when it was clear the temperature dropped below freezing. Now I just waited for a cloud to drift over and...hey...what happened? As soon as the cloud was above me the temperature was ABOVE freezing again. The IR radiation from the cloud warmed the air near the ground instantly--the minute it was over me---much faster than you'd see from convection or conduction. If you try this experiment, it works better with low (water droplet) clouds, since the radiation from them goes as temperature to the fourth power. Radiation goes (literally) at the speed of light.
EDIT: Maxx claims "The planet's atmosphere would reach about 255K without any greenhouse gases whatsoever. " but provides no evidence for this. The atmosphere in contact with the surface of the Earth would be at 255 K, but there is no evidence that it would be any warmer than that, and it would decrease with altitude. While oxygen and nitrogen may absorb some shortwave radiation, clearly it is not very much (we can see very well through pure oxygen and nitrogen). It should be expected that the atmospheric temperature would drop off at the adiabatic lapse rate of 10 K/km from 255 K until the stratosphere is reached.
If the surface of the Earth were removed and replaced with a perfectly transparent ball (for all wavelengths), then there is no evidence that the atmosphere would get anywhere close to 255 K. Why would it? Most of the sun's radiant energy would pass right through it without absorption.
I, too, am curious about what affect the non-GHGs have on the temperature of the earth. We know that GHGs do not trap heat and we also know that radiation happens at the speed of light. So even if there were any heating it would be passed on almost instantly.
GHGs can intercept certain photons and start to vibrate internally as a consequence. Guessing, I don't think that, of itself, constitutes a temperature change. I think the warming only happens when the GHG passes on the energy to the neighbouring N2 and O2 molecules. The Law of Equipartition is not met, for one thing.
In contrast, if N2 and O2 get warm they can't radiate the heat away. They really can trap heat. They would be heated by the surface of the earth to a temperature approaching 400K if the moon is anything to go by. Then that heat cannot now be radiated by the surface. It will be convected away only to come back to earth rather nearer the poles.
So, we have two ways of heating O2 and N2. One is supposed to heat the earth by 33°C and one is not. It seems contradictory or at least incomplete to me.
To my knowledge, a planet with a nitrogen/oxygen atmosphere, but no greenhouse gasses, would be approximately the same temperature as a planet with no atmosphere (except, of course, that it would be surface rather than atmospheric temperature). The only difference, afaik, would be from the gas moving some of the heat around, so that the night side would be a good bit warmer and the day side would be a good bit cooler. The presence of nitrogen and oxygen (or any other non-greenhouse gas) in the atmosphere does not change how much solar energy comes in, and makes very little change in how much solar energy leaves.
It is true that inert gasses will warm up when struck with photons. But, every photon that hits an air molecule is one that *doesn't* hit the surface, so that won't increase warming, just redistribute it a bit.
Without atmosphere, the day side of the earth would be super heated by the sun and solar radiation, and the night side would be hundreds of degrees below zero, with only cosmic rays and starlight to warm it. There hasn't been an increase of nitrogen and oxygen levels in the atmosphere.
Of course, Goddard's claim is nonsense. It makes the ridiculous claim that if a planet were cold because of the absence of the Sun, it would have no atmospheric pressure, citing the ideal gas law, PV = nRT.
The surface pressure of a planet's atmosphere has nothing to do with temperature, at least not unless one were to consider that some gases, like water vapor are added to an atmosphere by increasing temperature. The surface pressure of a planet is dependent on the gravitational attraction of the atmosphere to the planet; its weight. According to the ideal gas law, cooling a planet's atmosphere means that it occupies less space and has no effect on pressure.
Even climate skeptic, Roy Spencer, debunks claims to the effect that planetary surface temperature is due to the lapse rate.
http://www.drroyspencer.com/2014/04/skep... Note number 6.
But as far as the amount of the 33C warming due to Earth's atmosphere, almost all of that is due to greenhouse gases. Oxygen and nitrogen do absorb a small amount of UV, visible and near IR light, but almost all of the warming is due to greenhouse gases.
UV absorbed by ozone does warm the stratosphere.
Mars is further from the Sun than Earth and is missing carbon dioxide's dance partner; water vapor.
Madd Maxx
Because Earth's surface would reach about 255K without any atmosphere whatsoever. Earth's atmosphere is almost transparent to Sunlight. Earth's surface is opaque.
"Steven Goddard" is a fake person and nothing he says is supportable. Why not just make up your own stuff?
The 33 degrees you refer to is not the difference without atmosphere, it is the difference in temperature of the lower atmosphere without greenhouse gases. Without atmosphere, obviously there is no temperature of the atmosphere.
Nitrogen and Oxygen are both decreasing in the earth's troposphere. They are obviously cannot be causing global warming unless there is some unknown negative relationship.
I am specifically referring to the 33 degree increase from our atmosphere and the earth with no atmosphere.
http://redplanet.asu.edu/?p=2592
Note that this discusses the adding of 0.5 bars of nitrogen causing a 13 degree increase. Currently we have 0.78 bars of nitrogen. So can we assume that nitrogen causes around 13 degrees of the 33 degrees we currently see? How much of the warming of the earth is due simply to the thickness of the atmosphere of the earth?
Note that Goddard argues that thickness makes up most of the effect of the warming.
Now while it is silly to assume that thickness makes up the entire effect, given the ability of a more dense column of air to retain heat more than a less dense column of air, how much of the warming is actually solely due to the thickness of the atmosphere?
About 89% of total atmospheric warming is due to Nitrogen and Oxygen.
Oxygen and Nitrogen are not classified as Greenhouse Gases because they don't heat due to absorption of infrared, however they do absorb incoming radiation and they do heat, it's just not in the infrared range that they absorb. They absorb in the high energy shortwave part of the spectrum (not infrared).
The Greenhouse Effect is narrowly defined as ONLY that warming which is caused by absorption of infrared --- and that is only about 11% of total atmospheric warming.
How do we know this? Because we know that the Earth's average temperature is about 288K and the Greenhouse Effect only provides about 33K of that. The planet's atmosphere would reach about 255K without any greenhouse gases whatsoever.
Wiki says: "Greenhouse gases greatly affect the temperature of the Earth; without them, Earth's surface would average about 33 °C colder..." http://en.wikipedia.org/wiki/Greenhouse_...
"Gamma rays, X-rays, and ultraviolet radiation less than 200 nanometers in wavelength are selectively absorbed in the atmosphere by oxygen and nitrogen and turned into heat energy." http://www.eoearth.org/view/article/1560...
And most of the heat caused by the Greenhouse Effect is due to water vapor, not CO2.
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Climate Realist is the only one in this thread so far that understands that oxygen and nitrogen do in fact heat due to absorption of shortwave radiation (not infrared). And oxygen and nitrogen comprise 99% of the gases in the atmosphere. If they heat at all, and they do, then the impact of those gases heating will naturally far overwhelm anything the Greenhouse Gases can do to warm the planet.
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All mass absorbs and releases thermal energy. It's a fundamental property of mass. How much absorbed and released is the question.
Nitrogen and oxygen are no different because both have mass.
To claim that these gases will not retain thermal energy that is added to it is a fundamental violation of the laws of physics.
Zero. O2 and N2 are not greenhouse gases
Microwaves are being broadcast all over the planet. These microwave beams are exciting Oxygen suspended in the atmosphere. This Oxygen is in the form of H2O. So when the Microwave beams exite these molecules of water they split apart, giving off Heat and Oxegen, and Hydrogen. Thus adding to global warming. I'm not a smart guy, but I'm pretty sure this is an unmentioned problem in our modern world.
