1. A temporary cessation of the foehn at the ground, due to the formation or intrusion of a cold air layer that lifts the foehn above the valley floor. This often happens for a few hours in the early morning, just before sunrise, and brings about a rapid fall of temperature and increase of relative humidity that persists for an hour or more. Pause may also result from the advance or retreat of the mountain wave pattern that often accompanies the foehn. 2. The boundary between foehn air and its surroundings.