Csapadékevapotranszspirációindex

Csapadékevapot is a meteorological term used in Hungarian for the evaporation of precipitation while it is still falling through the atmosphere, before reaching the ground. In many contexts this phenomenon is known in English as virga. The concept describes rain or snow that evaporates or sublimates as it passes through a layer of unsaturated air beneath the cloud, so the visible precipitation may not reach the surface.

The process occurs when the air below the cloud is drier than the air inside the cloud, or when it is warmer and drier than the falling hydrometeors. Droplets lose mass through evaporation, and snowflakes may sublimate if conditions are cold and dry enough. The rate of evaporation depends on humidity, temperature, wind speed, and the size of the precipitation particles. If the environmental conditions are right, the precipitation may dissipate entirely before it reaches the ground, although visible shafts or wispy trails can still be observed beneath the cloud base.

Observationally, csapadékevapot may appear as shrinking rain shafts extending from the cloud that fade before contact with the surface. Weather radar can sometimes detect heavier echoes aloft with little corresponding ground rain. The phenomenon has implications for rainfall estimates, hydrological modeling, and agricultural planning because surface precipitation can be significantly less than what is inferred from cloud or atmospheric observations. It is more common in dry or semi-arid regions and during episodes of dry air intrusion into precipitation systems.

See also: virga, evaporation, sublimation, precipitation.