system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it colder at higher elevations? If heat rises, shouldn't it be warmer the higher up a mountain you go and colder at lower elevations?
gpt
"Hot air rises" is a bit of a misnomer, because it demands the assumption of constant pressure.  The real physical mechanism at work is that "less dense air rises", which is a function of both temperature and pressure.  As air rises, it expands to meet environmental pressure, doing work and cooling.  At a constant pressure level, hotter air is less dense, and rises and cools until it reaches a level where it matches the density of its environment.