Eli5: how does the earths atmosphere work? E. G how does the oxygen not fade away into the cosmos

Question

I’ve had a conversation with a guy that claimed “it’s a myth”. An obvious face-palm, I know, but I realized I’d like to know.

In: 71

Answer 1

Air doesn’t float off into the cosmos for the same reason that water doesn’t float off.

Air is heavy.

We don’t notice, because we’re used to it. But air has weight.

Also, that weight is what clouds float on. Clouds are floating on air the the same way a boat floats on water.