green flash

American

noun

a green coloration of the upper portion of the sun, caused by atmospheric refraction and occasionally seen as the sun rises above or sinks below the horizon.

green flash British

noun

astronomy a flash of bright green light sometimes seen as the sun passes below the horizon, caused by a combination of the dispersion, scattering, and refraction of light

"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

Etymology

Origin of green flash

First recorded in 1910–15

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

When a particle is caught, a bright green flash appears, confirming that the trap has successfully grabbed a glowing, perfectly round aerosol particle.

From Science Daily • Nov. 24, 2025

Another, Marco, said he experience a light green flash.

From Seattle Times • May 22, 2024

It takes only a moment, like a green flash, to see something made long ago with entirely new eyes.

From New York Times • Mar. 13, 2023

When the power was switched on, the robot sparked to life with an uncharacteristic bright green flash accompanied by wisps of smoke.

From Los Angeles Times • Jul. 8, 2022

I’d just picked up the latest Americaman comic to read for the millionth time when it happened—a bright green flash lighting up the sky outside the window.

From "Klawde: Evil Alien Warlord Cat" by Johnny Marciano and Emily Chenoweth

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023