Have you ever seen rain showing up on a radar, but when you look out your window you don’t see anything. 22News Storm Team Meteorologist Kelly Reardon explains the phenomenon known as virga.
Sunday morning something interesting popped up on the radar. It’s an atmospheric phenomenon and you might’ve seen it before.
If you’re watching the 22News Storm Team forecast, or even just looking at a radar image on your phone, and you see it’s raining at your location, but you look out the window, and there’s nothing. This is something called virga.
Rain, as opposed to snow, forms when there’s a thick layer of warm air above the surface. But with virga, a layer of exceptionally dry air near the surface causes the rain to evaporate before hitting the ground.
The thicker the dry layer, the less likely rain is able to make it to the surface. The radar isn’t lying about the rain. The farther you are from the radar, the higher in the atmosphere you are looking because it tilts upward.
So the radar is reading rain, but since the beam isn’t pointing parallel closer to the ground, it doesn’t pick up that the rain is not falling all the way down.
In person, virga tends to look like streaks extending down from the bottom of a cloud.