Of course heat lightning is just lightning seen from a long distance, but how did the concept that it had anything to do with heat start?
Walter Fox, Ferguson, Mo.
Dear Walter,
You’re correct that heat lightning is just ordinary lightning from a thunderstorm too far away for its thunder to be heard. With summer t-storms routinely building in excess of 50,000 feet, the lightning is visible at distances beyond 125 miles to anyone with a clear view of the horizon. Often the thunderstorm cloud is actually below the horizon, not visible because of the curvature of the Earth’s surface, but the lightning emanating from the upper portions of the storm can still be seen. The term heat lightning came into prominence because the distant lightning was frequently observed on clear, hot summer nights.
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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.
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