system
Given the following post, respond as if you're commenting on Reddit:
human
So I know that heat rises, but why is that so?

It's almost an adage at this point, however what is the reasoning between heat rising? Does it have to do with air pressure?
gpt
Hotter fluids like air and water generally have a lower density. This means that a given volume of the hotter fluid is lighter than the cooler fluid. The heavier fluid sinks forcing the warmer one to rise. 

Heat doesn't rise. This is why you don't see heat "rising" in solids. This is also dependent on the differing weights, which is why you don't see heat rising in zero-g.