heat lightning

American  

noun

1. lightning too distant for thunder to be heard, observed as diffuse flashes near the horizon on summer evenings.

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heat lightning British  

noun

1. flashes of light seen near the horizon, esp on hot evenings: reflections of more distant lightning

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heat lightning Scientific  

1. 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.

2. See also sheet lightning See more at lightning

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Etymology

Origin of heat lightning

An Americanism dating back to 1825–35

Example Sentences

Many blazes are triggered by heat, lightning, winds and other factors that are harder to predict in advance.

From Los Angeles Times • Jan. 31, 2023

She recalled certain images: heat lightning traveling from cloud to cloud, tall grasses, gas flares on the horizon, droves of red-winged blackbirds.

From New York Times • Oct. 23, 2019

Through the dark humid air, Hardy could see mountains lit by sudden flashes of heat lightning, the boom of thunder echoing over the water.

From Washington Post

Most of the blazes have been started by heat lightning, and many are still out of control.

From Time Magazine Archive

She lay in the dark, propped up on the pillows, and stared at the lighter square of her window, at the heat lightning throbbing.

From "Tuck Everlasting" by Natalie Babbit