February 20, 1998 transcript #: 221-5 
Subject(s): virga, rain 

It’s listener question day here on The Weather Notebook.  Hi, I’m Dave Thurlow.  Today’s weather query comes from Tony Williams, who listens to us on WNCW in Spindale, North Carolina.   

“I have a question for you which is, what is virga and when and how does it happen?” 

Virga is any form or precipitation that doesn’t reach the ground.  There could be rain virga or snow virga.  But in either case, the precipitation evaporates somewhere on the journey from clouds toward earth.   Virga, which is spelled v-i-r-g-a, is pretty common and you’ve probably seen it but didn’t know it had a special name.  Mostly in the summer, virga can be seen falling away in streaks from the bottom of one of those puffy gray and white cumulus clouds on a crisp afternoon.  It looks like a torn drape or a curtain hanging from the cloud, but only down about halfway to the ground below.  Sometimes the air thousands of feet above the ground is moist enough to produce clouds and rain at the same time that the air closer to the ground is as dry as a bone.  So when rain falls in these conditions it evaporates on its freefall to earth.  So virga is technically virgin precipitation and its easy to spot its wispy form seemingly hanging in the air beneath its parent cloud.  Every other Friday we answer weather questions from listeners, so if you have a weather question, give us a call at 1-888-724-6001, or check our webpage at www.mountwashington.org.  We do our best to answer every question we get directly and we choose one every other week to put on the air.  If its yours, we’ll send you a Weather Notebook magic mug. 

Virga Clouds
From: A Field Guide to the Atmosphere (Peterson Field Guide)
V.J. Schaefer and J. A. Day. Boston: Houghton Mifflin Co. 1981.

Our show is a production of the Mount Washington Observatory with thanks to Subaru and the National Science Foundation.