Foehn, << fayn, >> is a warm, dry wind that blows down a mountainside. The air loses its moisture as it rises to the mountaintop. It is heated by compression as it comes down the other side of the mountain. Foehns occur in mountainous regions throughout the world. They blow frequently in the Alps, where the warm wind received its name. In the Rocky Mountains, a foehn is called a chinook (see Chinook ). These winds often bring rapid temperature changes. For example, the temperature at Havre, Mont., rose 33 °F. (18 °C) in one hour when a chinook suddenly arrived on Feb. 15, 1948. Foehns or chinooks cause snow to melt rapidly. The winds often make the climate of areas in which they occur much warmer than neighboring areas.
