Why does air cool as it rises through the atmosphere?
The first thing we must realize is that temperature and heat are two different things, they’re closely related but one can be affected while the other is not. We all know that warm air rises, if it didn’t the people in hot air balloons would be in trouble. This warm air will cool as it rises, but the air will not lose heat.
The surface of the Earth absorbs a great amount of heat energy from the sun. Some of this energy is transferred to the air on the surface; this air then rises and cools. It is lowering its temperature but not losing any energy, which is really all heat is. As the air rises the pressure on it decreases, there is less air on top of it forcing it down. The air will then spread out, it will become less dense, and the molecules of the air will literally expand due to this decrease in pressure. The energy that used to create a higher temperature in the sir is now being used to expand and hold the expansion of the molecules. AS you can see the energy is still present but the temperature has decreased.
This is called the adiabatic process, which is a term that implies that there is a change in temperature without the gain or loss of heat.
This link will provide more information including how this process is related to the formation of clouds.
http://ellerbruch.nmu.edu/cs255/mboutell/cloudadiabatic.html
