Dear Tom,
Is it true that lightning travels upward? I always thought lighting was the product of positive and negative fields crashing against other.
Carlos Figueredo
Dear Carlos,
Because positive and negative charges attract each other, they do not “crash against each other.” Rather, a lightning bolt consists primarily of a flow of negatively charged particles (electrons).
Meteorologists now understand that about 20 million lightning ground strikes occur in the United States annually. A great majority of those bolts (90-95%) are termed “negative,” meaning the flow of electric current is from a negative charge center in the cloud to the positively-charged ground. The remainder (5-10%) are “positive”, with current flowing from negative ground to positive cloud.
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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.
