Foehn effect

A thermodynamic phenomenon that gives rise to a very warm, dry, and turbulent wind, resulting from the adiabatic heating undergone by an air mass after crossing a mountain range and descending on the lee side, from the mountain summits to the bottom of the valleys, where the effect is felt most sharply. The air is originally humid and its temperature is considerably lower than what it ends up having after crossing the mountain obstacle. On the windward side of it, being forced to rise, the air progressively cools, losing much of its water vapor content in the upper stretch of the mountain, due to the formation of clouds and orographic precipitation. In that ascent, the cooling rate of the air is greater than the rate of the heating it experiences, through adiabatic compression, as it rushes downhill, on the lee side. The result is a superheated, dry wind, which causes a notable rise in temperature in the areas where it breaks through, doing so, moreover, abruptly and impetuously, with violent gusts. The word foehn is a variant of the German term föhn, with its origin in the Latin word favonius, which is the name given in Roman mythology to the gentle west wind. The foehn effect began to be studied in Switzerland, where episodes of high temperatures periodically occur as a consequence of the phenomenon described, even in the middle of winter, under a wind regime (initially cold) from the north. The foehn effect acquires special relevance in those places in the world where mountain ranges are arranged perpendicular to the dominant flow.