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Latest Walt Petersen Stories

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2011-04-27 13:42:29

Lori Keesey, NASA Scientists from NASA and other organizations are on a mission to unlock the mysteries of why certain clouds produce copious amounts of rain. In a field mission that is now under way, aircraft are carrying instruments above and into rain clouds. Meanwhile scientists are also getting rainfall measurements on the ground. This field campaign provides the most comprehensive observations of rainfall in the U.S. through the use of aircraft, spacecraft, remote sensing and ground...

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2011-02-25 09:00:13

By Dauna Coulter, Science @ NASA NASA atmospheric scientists got an unexpected chance to study a curious phenomenon called "thundersnow" when a recent storm unleashed it right over their heads. Walt Petersen and Kevin Knupp have traveled far and wide to study winter storms. They never dreamed that the most extraordinary one they'd see "“ featuring freakish thundersnow, a 50-mile long lightning bolt, and almost a dozen gravity waves -- would erupt in their own back yards. The storm hit...

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2011-01-26 09:40:00

A city that rarely sees snowfall, Huntsville, Ala., was blanketed the evening of Jan. 9 under several inches of snow following a winter storm that also produced a rare "thundersnow" or lightning flashes. This unique weather event allowed scientists at NASA's Marshall Space Flight Center and the University of Alabama in Huntsville the opportunity to assemble one of the most detailed snowfall datasets on record for the deep southern tier of the continental United States. Scientists in...

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2010-08-18 08:30:00

Rain drops are fat and snowflakes are fluffy, but why does it matter in terms of predicting severe storms? We've all seen fat rain drops, skinny rain drops, round hailstones, fluffy snowflakes and even ice needles. This summer, NASA researchers are going to get a look at just how much these shapes influence severe storm weather. To do it, they'll have to look inside the guts of some of the world's fiercest storms. NASA recently assembled a team of hurricane scientists from across the country...

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2009-04-23 08:20:00

Imagine a monster tornado is ripping through a neighboring county and bearing down on yours. If you live in north Alabama, your forecasters are well prepared to tell you when to seek shelter. The National Weather Service there shares a building "“ the National Space Science and Technology Center "“ with NASA's Short-term Prediction Research and Transition, or SPoRT, Center. SPoRT puts state-of-the-art NASA satellite data directly into forecasters hands, arming them to recognize...

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2007-03-05 11:05:00

People have lived with rain and snow for millennia, and scientists have studied weather for more than a century. You might think that, after all that time, we would have precipitation pretty much figured out. And you'd be wrong. "It's amazing how much we don't know about global patterns of rain and snow," says Walt Petersen, an atmospheric scientist with the National Space Science and Technology Center (NSSTC) and the University of Alabama (UAH) in Huntsville. For instance, how much snow...

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2006-09-22 08:40:00

Here's something fun to try in your kitchen: Go to the freezer, open the door and pry loose an ice cube. Next, look around the freezing compartment for some frost"”the crystalline fuzz that loves to coat your frozen English peas. Found it? Rub the ice cube gently across the frost. Nothing happens. Well, what did you expect, a bolt of lightning? Actually, that's just how lightning gets started. Miles above Earth in cumulonimbus clouds, tiny ice crystals are constantly bumping against...