Virga (from the Latin virga, meaning rod or branch) is a form of precipitation visible as streaks or curtains of rain, snow, or ice hanging from the base of a cloud that evaporate or sublimate completely before reaching the ground. This phenomenon is most frequent in dry environments and with mid-level clouds such as altocumulus and altostratus. Virga occurs when falling precipitation encounters a layer of dry, warm air below the cloud. The drops or crystals absorb heat from the surrounding air during their evaporation or sublimation, cooling the air in that zone. This evaporative cooling can generate downdrafts that, if sufficiently intense, become microbursts with potentially destructive surface winds. Virga is easily identifiable: it appears as diffuse streaks or filaments hanging from the cloud that fade before reaching the horizon. It is especially photogenic at sunset when low-angle light illuminates the precipitation curtains. Virga is very common in continental interiors during summer, when the lower atmosphere is dry and vertically developing clouds produce precipitation that does not survive the descent. The presence of virga can indicate approaching changes in atmospheric conditions.