[paul.fr]

Hot air rises, so what happens to cold air?

[another_someone]

The only reason hot air rises is because cold air falls, and displaces the hot air upwards.  If there was no cold air, then the hot air would not rise (OK, if there was no cold air, one could ask in relation to what was the hot air hot - so maybe that is a silly point to make).

[lyner]

If you stood with bare feet by an open freezer door then you would definitely say that cold air falls.

[lyner]

Convection is nature's own heat engine; a hot source, a cold sink , resulting in mechanical work.