The Collaborative International Dictionary
Air cooling \Air cooling\ In devices generating heat, such as gasoline-engine motor vehicles, the cooling of the device by increasing its radiating surface by means of ribs or radiators, and placing it so that it is exposed to a current of air. Cf. Water cooling. -- Air"-cooled`, a.
Wikipedia
In all cases, the air has to be cooler than the object or surface from which it is expected to remove heat. This is due to the second law of thermodynamics, which states that heat will only move spontaneously from a hot reservoir (the heat sink) to a cold reservoir (the air).
Usage examples of "air cooling".
We stood on the top of the berm, the highway busy below, the air cooling, the wind gusting.
The shadows were deep now, the air cooling, but the topless towers of Ilium were still lighted by the red sun setting in the west.