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Viewing Single Post From: The giant space ship example
Chris Ho-Stuart
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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.
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The giant space ship example · Physical theory for climate