Virga is a meteorological phenomenon characterized by an observable streak or shaft of precipitation that evaporates or sublimates before reaching the ground. In meteorology, it is distinguished from a precipitation shaft, which refers to moisture that successfully reaches the surface. At high altitudes, this precipitation typically begins as ice crystals before melting and subsequently evaporating due to compressional heating caused by increasing air pressure closer to the earth.
This phenomenon is frequently observed in both desert and temperate climates. Notable regions where virga commonly occurs include the Western United States and the Canadian Prairies in North America, as well as parts of Australia, North Africa, and the Middle East.