Dear Tom,
How far can the sound of thunder travel?
William Tabbert, Cary, Ill.
Dear William,
Tucson, Ariz., lightning expert Ron Holle tells us thunder is rarely heard beyond 10-15 miles from the lightning discharge, and 25-30 miles is an approximate extreme upper limit of audibility.
However, thunder loses energy more quickly and is muffled rapidly when it passes through a shield of heavy rain. Its audible distance can be reduced to just a few miles in such situations.
A lightning bolt heats the channel of air through which it passes (a half-inch in diameter, or less) to above 50,000 (degrees) F in millionths of a second. That heated air expands explosively, generating the sound waves that we hear as thunder. Count the seconds between “flash and bang” and divide by five. That’s the distance, in miles, of the closest portion of the lightning bolt to you.
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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.
