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Rain & snow

Why does the sky appear clear after it rains?  Shylaja, Bangalore, India

Before rain can form and fall from the sky, atmospheric air rises.  After the rain, the cooled air sinks, and brings down clean air from on high.  That's why the air appears clear --- it contains much less pollutants.

What are the rainfall totals across the USA for the past 3 years?  Barb, Chicago, Illinois, USA

Please click here for a map showing the USA precipitation currently and, also, the archived maps that go back to the year 2005.  The archives display the rain and snowfall also by the month, through the years.  The maps show observed, normal, departure from normal and percent of normal.  Courtesy of NOAA.
 

Winds

Do tornados spin differently in the Northern and Southern hemispheres?  HurricaneGeek, West Palm Beach, Florida, USA

Tornados in the two hemispheres usually rotate in different directions — counterclockwise in the Northern Hemisphere and clockwise in the Southern.  However, we have observed clockwise rotating tornados in the Northern Hemisphere — normally waterspouts, dust-devil type land tornados or whirls around the rim of a supercell thunderstorm (mesocyclone).  Even more surprising, we've documented cases where tornados rotate in opposite directions under the same thunderstorm at the same time.   The online  tornado FAQ, by Roger Edwards, NOAA

What do tornados sound like?  Sky, Someplace, World

Most commonly, like the rumbling roar of a nearby train.  Some tornados, though, sound like a waterfall or the whooshing noise of air streaming by open windows of a fast-moving car.   The online  tornado FAQ, by Roger Edwards, NOAA

Do tornados really skip?  It seems like they do, because one skipped over our house, but caused heavy damage on both sides of us.  April, Montgomery, Alabama, USA

Not according to the definition of a tornado given by the Glossary of Meteorology, which says the tornado must always touch the ground.  What probably happens, when we think a tornado skips, is the tornado was too weak to do much damage there, or more than one tornado was rampaging through the location.  The online  tornado FAQ, by Roger Edwards, NOAA

On a very still, calm day I was walking in woods and heard a sound like an express train, it was a wind approaching that tore past me with great energy and speed and disappeared into the distance. The phenomena lasted approximately 4 or 5 minutes. Everything returned to being still and calm. Is their a name for this type of wind and what causes it? Chris, Tamworth, England

A similar wind hit me when canoeing on a desert lake in the southern part of New Mexico.  I asked lead forecaster Roger Edwards of NOAA's Storm Prediction Center what could have caused such blasts.  He said, in your case, "I suspect an intense outflow wind from thunderstorms where the thunder was too far away to be heard."  In my case, "a burst of strong downslope winds from nearby mountains also might have caused such a rush."  But, without weather maps or satellite or radar images to consult, "it's hard to say."

Lightning

Is there a higher chance of lightning hitting a male than it hitting a female.  Jerry, Beaumont, California

Yes, Jerry.  Of the 28 lightning-caused deaths in 2008, the NOAA reports that 79% were male and 36% were males between the ages of 20-25. 

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