All Weather News

Rain, Evaporation, Virga and Downbursts

23 May 2017, 5:01 pm

Television meteorologists will many times use the word virga describing rain falling from a storm into much drier air and evaporating before it reaches the ground. But just what are they describing?

Virga is a phenomenon where rain is being produced from a cloud but the raindrops never reach the ground due to evaporation.
Virga may look like a rain shower on radar but an observer will see a
streak or shaft of precipitation falling from a cloud noticeably dissipating before ground level.

Evaporation and sublimation of the rain falling will also remove heat from the air making it more dense.  This now heavier parcel of air can descend rapidly creating micro-bursts that are hazardous to aviation and can cause strong winds at the surface. In more humid environments rain may not completely evaporate giving us what’s called a wet micro-burst.

For Weather Nation: Meteorologist Mike Morrison

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