Noun

1. A rare phenomenon observed in morning or evening when the sun is crossing or immediately below the horizon, in which a momentary flash or ray of green light appears above the upper rim of the solar disk, caused by refraction of light in the atmosphere.

Quotations

• 1929, J. A. Fleming, "Observations of Green Flash," Science, New Series, vol. 69, no. 1785, p. 298:

  Frank T. Davies, physicist on board the City of New York, en route to the Antarctic regions with Byrd Antarctic Expedition, reports as follows on a green flash observed off Bermuda on the evening of August 29, 1928.