“Diatomic molecules such as oxygen and nitrogen don’t absorb significant amounts of radiation either from the Sun or Earth’s surface. They get warm by acquiring kinetic energy through diffusion which involves molecular collisions with the surface and other air molecules. ”
Yes.
So the vast majority of gases in Earth atmosphere are Nitrogen, Oxygen, and Argon. And the only way to heat up these gases is by acquiring KE from molecular collisions and with the surface. Or a surface.
Or from other gases or from solids and liquids.
So 99% of atmosphere are not directly warmed by radiation. Correct?
So I could say we are 99% towards getting to the point.
The kinetic energy (KE) is divided equally between six degrees of freedom – three translational DOF’s, 2 rotational DOF’s and one vibrational DOF as per the Equipartition Theorem. Temperature is affected by the mean KE, not the total KE in a region, so density has nothing to do with it.
This is interesting:
http://en.wikipedia.org/wiki/Equipartition_theorem
It’s mostly about quantifying specific heat of compounds. And it says:
“More generally, in an ideal gas, the total energy consists purely of (translational) kinetic energy: by assumption, the particles have no internal degrees of freedom and move independently of one another. Equipartition therefore predicts that the average total energy of an ideal gas of N particles is (3/2) N kB T. ”
And to repeat:
“More generally, in an ideal gas, the total energy consists purely of (translational) kinetic energy: by assumption, the particles have no internal degrees of freedom and move independently of one another. ”
What is ideal gas?
“At normal conditions such as standard temperature and pressure, most real gases behave qualitatively like an ideal gas. Many gases such as air, nitrogen, oxygen, hydrogen, noble gases, and some heavier gases like carbon dioxide can be treated like ideal gases within reasonable tolerances.”
http://en.wikipedia.org/wiki/Ideal_gas
One can treat CO2 as ideal gas, I believe in terms conditions in Earth Atmosphere, we remove the qualifier of “within reasonable tolerances”,
but maybe I am wrong. But what isn’t a ideal gas in our atmosphere is H2O gas.
So I going assume as generally assumed that all gases in Earth Atmosphere, except H20 are ideal gas, and that with ideal gases “the particles have no internal degrees of freedom and move independently of one another. ”
Now we know, H20 affects the atmosphere’s lapse. We have Dry adiabatic lapse rate and Saturated adiabatic lapse rate.
http://en.wikipedia.org/wiki/Lapse_rate
If H2O was a ideal gas, we would not have the terms, Dry adiabatic lapse rate and Saturated adiabatic lapse rate. But we live on water planet, with water everywhere, so we need them.
So seems to me handled the CO2 part of the atmosphere, but it tiny part of the missing 1 percent: .04 %.
So other than water, the reference you gave says:
“More generally, in an ideal gas, the total energy consists purely of (translational) kinetic energy”
“Physics / General Physics) the energy of motion of a body, equal to the work it would do if it were brought to rest. The translational kinetic energy depends on motion through space, and for a rigid body of constant mass is equal to the product of half the mass times the square of the speed. ”
http://www.thefreedictionary.com/Translational+energy