Just a thought...?

Question

If hot air rises and its colder the higher up you go...why dosen't it cancel out?

Answer 1

think of hot air as fast moving molecules. then these are going to travel higher before gravity brings them back down.

a "hot" air molecule at sea level may travel up for a long time, and slowly lose its kinetic energy (a quantity losely linked to temperature) to potential energy as it climbs the gravitational potential well- so it will slow down, losing "heat", as it rises.

this si similar to how a human loses velocity as they jump into the air- a jumping human rises like hot air does, but as they rise, they slow down.

Answer 2

The fact that it is colder the higher up is exactly why the hot air goes up there, to even it out. But it would take a lot of hot air to make a significant change in the entire atmosphere. In an enclosed space you could achieve equillibrium.

Answer 3

It does 'cancel out' as you put it. It cools as it rises. Conversely, air moving downward gets warmed.

These processes are termed  'adiabatic' meaning no external heat source is needed. They are very important in driving the weather. They explain the rain in the mountains, for example.