Dear Tom,
Is it possible to measure the diameter of a lighting bolt? What shapes does lightning have? Small? Big? Zig-zag?
Dan and Joe
Dear Dan and Joe,
Researchers have, indeed, ascertained the diameter of lightning bolts: The current-carrying channel of a bolt is about one-half inch in diameter, often less. University of Florida lightning expert Dr. Martin Uman says, “Lightning diameter measurements have been made in two ways: By examining the interaction between lighting and objects, and from photographs.” When lighting strikes an object such as a rock, it leaves visible damage, such as burn marks, that can be related to the channel diameter. Photographs show that lightning is zig-zagged in 100-yard steps, within which are 10-yard steps, within which are twists on a scale measured in inches.
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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.
