|
|
|
|
Winter Lightning
09/27/2002
Listen in RealAudio 
Hi, I'm Bryan Yeaton, and this is The Weather Notebook. We got a question on our answering
machine from George Wu of Kennett High School in Conway, New Hampshire. Here's what he wanted
to know.
GEORGE: Bryan, why doesn't it thunderstorm in the wintertime?
Good question. Let's go to a weather expert, Nicole Plette, our own Staff Meteorologist at the
Mount Washington Observatory. Nicole, why don't we get thunder and lightning in the
winter?
NICOLE: The storms that create lightning and thunder are generally produced in the summer
because the main driving forces for those storms are heat and moisture. Warmer air can hold
more moisture than, say, cooler air. The water, basically, adds to the storm's energy. As the
water condenses, it releases latent heat and that latent heat is in the form of energy and
provides energy for the storm.
BRYAN: What do you need to make lightning?
NICOLE: Lightning is made in convective storms. A convective storm are those types of storms
where the cumulus clouds are really tall and high and fluffy and you see them climbing very
tall into the sky.
BRYAN: So what are the factors that you need to make one of these thunderstorms in winter
conditions?
NICOLE: We need to have a lot of water available – usually that happens from a storm system
that has crossed over a large body of water – it picks up a lot more moisture that way.
That's the main thing, and then, also, you would need a very low pressure due to the fact that
that would have higher winds and would cause more friction.
BRYAN: So it would be associated with a very intense storm?
NICOLE: Definitely! In the wintertime, for sure.
BRYAN: And is that what they call "thunder snow"?
NICOLE: That's exactly right. Thunder snow is a rare occurrence but it does happen.
Thanks to Nicole Plette for that answer, and to George Wu for the question. Our program is
produced with support from the National Science Foundation, and Subaru of America. Thanks
today to marketing manager Melody Nester and executive engineer, Sean Doucette.
|
|
