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Viewing Single Post From: The giant space ship example

Chris Ho-Stuart
Dec 15 2011, 04:23 AM
Dec 15 2011, 12:45 AM
Can we also assume that Nitrogen in addition to being almost totally transparent, also does not transfer energy [lose heat/energy] other than imparting energy through collision. That molecule collision in the atmosphere among exclusively nitrogen gas can impart kinetic energy, but doesn't cause nitrogen emit photons [radiate heat].

And that collisions of nitrogen gas with CO2 [or other gases] could cause these other gases to emit photons.
In a mixed gas, all the different kinds of molecules end up at the same temperature, as they keeping colliding with each other. As well as this, all the molecules absorb and emit radiation depending on their own radiative properties.

Nitrogen has almost no interaction with radiation in either visible or thermal-IR bands. It does not absorb, or emit, those frequencies; it is transparent. Greenhouse gases are gases that absorb or emit in the thermal-IR bands, which are the bands where you get radiation emitted from a surface such as Earth's, with temperatures up to 320K or so. A mixture of N2 with even a very small amount of a gas that interacts strongly with thermal-IR will be heated up very effectively by thermal radiation. It's only the greenhouse gas that actually absorbs the radiation itself. But thereafter the energy is rapidly shared around with other molecules in the gas, so that the whole gas heats up.
So I getting that you saying that CO2 absorbs radiation- from other greenhouse gases or the ground.
And that a molecule of N2 can collide with the CO2 and gain that energy.

And if so, I am not sure I can agree.

As I understand it, the N2 molecule can have 3 "types" of energy. The speed the molecule is traveling. The spin of the molecule. And vibration of the molecule.

I am uncertain about the vibration of the N2 molecule- the amount or significance
of any N2 vibration. I don't know how to begin to quantify it.
The spin of N2 molecule I also don't understand very well.

The velocity of the molecules seems the most obvious and most understandable.
It seems to me that the most significant "element" of any gas temperature is the velocity
of the gas molecules. No molecule speed- no temperature.

Now, if CO2 molecule could transfer energy to a N2 molecule, how would this energy be expressed?

Would it increase the N2 molecule's velocity?

I tend to believe it's asymmetrical.

I think a CO2 molecule absorbs a part of infrared radiation. I don't know how long it holds this energy. Or how much energy it can absorb. I think it could release this energy when it's in a collision. And therefore the rate absorption and emission could be related to rate of collisions.

I think another possibility is that CO2 also gets energy from collisions [it apparently does this with a CO2 laser, so it could also do it in a atmosphere] would transform motion of gas molecules into radiate energy or maybe it converts spin and/or the vibrational energy.
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The giant space ship example · Physical theory for climate