lightning too distant for thunder to be heard, observed as diffuse flashes near the horizon on summer evenings.
Origin of heat lightning
An Americanism dating back to 1825–35
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for heat lightning
Historical Examples of heat lightning
Then the heat-lightning smile played about the hollow face again.
It reminded the other man of heat-lightning on a dark skyline.
It makes you feel like heat-lightning just to watch 'em fly!
Mrs. Bolton kept a grim silence, against which her husband's babble of optimism played like heat-lightning on a night sky.
But now and then, for an instant, the post sprang into sight out of the blackness to the weird play of the heat-lightning.
British Dictionary definitions for heat lightning
flashes of light seen near the horizon, esp on hot evenings: reflections of more distant lightning
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
heat lightning in Science
Intermittent flashes of reddish or orange light near the horizon, usually seen on a hot summer evening and unaccompanied by thunder. Heat lightning is thought to be the reflection of distant lightning on clouds. Its color is believed to be due to the refraction of light in the atmosphere. See also sheet lightning. See more at lightning.
The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.