Dear Tom,
As a child I always heard the term “heat lightning,” when you see a flash behind a cloud but there is no actual storm. This was brought up at an outdoor reception the other night and brought a lot of discussion about the weather. The majority of us agreed on it being heat lightning.
Tommie
Dear Tommie,
You have expressed a widespread misunderstanding about lightning. The fact is, heat lightning is always storm-generated lightning–but it is so far away that its thunder cannot be heard.
If intervening clouds do not block the luminosity generated by lightning, it is easily possible to see lightning more than 50 miles from its point of origin (and sometimes more than 100 miles), whereas thunder, the sound generated by lightning, can rarely be heard beyond 15-20 miles.
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN-TV News at noon and 9 p.m.
Write to: ASK TOM WHY, 2501 Bradley Pl., Chicago, IL 60618 or asktomwhy@wgntv.com (Mail volume precludes personal response.)
WGN-TV meteorologists Steve Kahn, Richard Koeneman and Paul Dailey plus weather producer Bill Snyder contribute to this page.
