Dear Tom,
Can there be thunder without lightning?
Richard Waller
Dear Richard,
By definition, thunder is the sound generated by lightning, so there can be no thunder without a lightning flash.
Even though the primary current-carrying portion of a lightning bolt is less than one-half inch wide (although it can be many miles in length), the lightning spark actually heats the air through which it travels to 50,000 (degrees)F or more. Such extreme heating causes air to expand explosively, initiating sound waves that we hear as thunder.
Thunder is rarely heard beyond 15 miles from the lightning discharge, and 25 miles is an approximate extreme upper limit of audibility. Also, heavy rain greatly reduces the distance that thunder carries.
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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.
WGN-TV meteorologists Steve Kahn, Richard Koeneman and Paul Dailey plus weather producer Bill Snyder contribute to this page.
