Definition of green flash in English English dictionary
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
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.