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DS8 asked me a question this morning that I'm not sure I have an accurate answer for, so I'm hoping someone here might be able to help me.

We were talking about how, when it's 0 degrees out like it is today (or less cold, but below freezing), how the exhaust from cars condenses as it meets the air, much the way our breath does. We talked a bit about gas particles freezing. And then he asked why the air all around us doesn't condense at such low temperatures. Obviously there's snow, but that's when there are clouds with moisture in them. Why don't the air's gaseous particles freeze up around us. Is it simply that there's not enough moisture at such low temperatures on a non-cloudy day? I talked about different freezing points, but I'm not sure that's entirely accurate, or if I'm overthinking my answer.

Anyone have a fairly simple explanation that could help me? TIA!

http://www.google.com/#q=boiling+point+of+air

The different components of air are going to have different boiling points. You can google on freezing point of oxygen, nitrogen, etc. Of course, before that they will liquefy.

Short answer: you seem to have given him the right info, that it's just not cold enough.

Thanks, lucounu!

Here's a link to a discussion about whether carbon dioxide could ever have frozen out of the Earth's atmosphere that does a fairly good job of discussing the relevant issues, in case more info is required or desired.

We have recently been talking about the opposite of that phenomenon- sublimation. We have been looking up quite a few things online related to this recently but hadn't thought about the opposite. The word for going from gas to solid, by the way, is deposition.
mnmom--I'm guessing from your name you must be in Minnesota too. Cold weather always makes for science lessons around our house too