noun
green flash
An optical phenomenon where a green spot is briefly visible above the sun at sunset or sunrise, under clear atmospheric conditions.
夕日が沈む瞬間、水平線に緑閃光が見えることがある。
At the moment the sun sets, a green flash can sometimes be seen on the horizon.
Compound of 緑 (ryoku, 'green') and 閃光 (senkō, 'flash'), describing the brief green light observed at the edge of the sun.