concept

Adiabatic lapse rate

The rate at which air cools as it rises and expands under falling pressure. On Earth, dry air loses about 10°C per kilometre of altitude - which is why mountain peaks are frigid. The rate scales with gravity and inversely with the air's heat capacity: Pandora's weaker gravity and heavy, humid, heat-rich atmosphere make its air cool far more slowly with height - enough to leave the floating mountains warm and watered instead of frozen.