Preface- I am a scum noob who doesn't know much. Why does a compressed gas cool a container down when released? I mean in terms of imaging the actual gas molecules moving around. For instance, I can imagine why water on the skin evaporating could cool a person down. The body transfers kinetic energy to the water and then some of the really fast most energetic water molecules fly off, thus taking that energy with it. If you open the valve on a compressed gas container shouldn't the gas just fly out and not take any extra kinetic energy with it?