Dear Tom,
Is there a way to measure the length of a bolt of lightning? If so, what’s the longest ever recorded?
Buddy, Elgin, Ill.
Dear Buddy,
Lightning bolts can be incredibly long, and a variety of techniques are used to make that determination. Photography is the most straightforward way to determine the length of a lightning bolt, but the disadvantage is that lightning within clouds cannot be photographed.
Because lightning channels are good electric conductors, they reflect radar pulses just as solid objects do, and we can utilize radar to measure channel lengths. The duration of thunder also allows us to approximate lightning-bolt length.
These techniques, and others, yield astonishing results. As early as the 1950s, radar studies showed horizontal lightning channels 90 miles in length. That is the distance from Chicago to Milwaukee.
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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.
