Mountain breeze and valley breeze

A mountain breeze and a valley breeze are two related, localized winds that occur one after the other on a daily cycle. They are not the same as katabatic winds, which are larger and stronger.

Mountain and valley breezes form through a process similar to sea and land breezes. During the day, the sun heats up valley air rapidly. Convection causes it to rise, causing a valley breeze. At night, the process is reversed. Mountain air cools rapidly at night and "falls" downslope, causing a mountain breeze.