When moist air rises over a mountain barrier, it cools at the slow saturated adiabatic lapse rate; precipitation is common. Once past the mountains, the air, now much drier, descends, warming at the dry adiabatic lapse rate, higher than the saturated rate by some 3 °C/1 000 m. A dry, warm, gusty wind, which can reach gale force, results. In summer, desiccation brings a serious risk of bush fires; in winter, snow melt can be rapid. See T. McKnight and D. Hess (2000) on föhn/Chinook winds, and Chan (2005) Croatian Met. J. 40 on föhn winds in Hong Kong.
Subjects: Meteorology and Climatology.