Dear Tom,
The thunder I heard recently was all “crashing” as contrasted with “booming” or “clap” sounds. Is there a correlation between the “voiceprint” of thunder and the lightning which causes it?
Jean SmilingCoyote, Chicago
Dear Jean,
A strong correlation exists. A lightning spark heats the air through which it travels to 50,000(degrees)F, causing it to expand explosively, initiating a shock wave that we hear as thunder.
Lightning expert Dr. Martin Uman explains that if a portion of the lightning spark is perpendicular to you, all points on that portion will produce sound that arrives almost simultaneously at your ears. The result is a high-intensity “crash.” However, if much of the lightning channel is along your line of sight, sound arrival times vary, and the resulting thunder is a low-intensity rumble.
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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.
