Quote:
Originally Posted by Hans Rancke-Madsen
I'm also hoping that someone knowledgable on the subject could tell me who is wrong here, Anderson, me, or my debater.
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Hard to say. The relevant phenomenon is called "scale height", H = kT/(g mu), which says the pressure of the atmosphere falls off exponentially , P = P0 e^(-z/H). In ideal gases in still air in should apply to all the gas partial pressures independently, and therefore produce some of this kind of segregation, though at survivable temperatures scale heights tend to be many kilometers, you'd need a lot of dramatic relief, or I suppose really high gravities, to get really big variations. The difference in CO2 molecular weight mu = 44, vs 32 for oxygen is not huge.
However. Here on Earth though, the atmosphere below about 100 km (the "homopause") fails to behave ideally and keeps essentially the same composition, probably because it is mixed by weather. Above that it starts behaving closer to ideally, and differences in scale height are partly why the really thin outer layers of all atmospheres tend to be dominated by hydrogen and helium molecules, atoms and ions - the other factor being composition of the solar wind.