Green flash is a rare phenomenon that occurs at sunset or sunrise when a small portion of the sun appears as a green spot, visible above the sun's upper rim. It lasts for only a few seconds and is a spectacular sight for those lucky enough to witness it. However, the term green flash has several synonyms as well. Some of them include emerald flash, green gleam, green ray, and green burst. Each of these synonyms makes use of the word green to describe the vivid color that appears in the sky, but adds other adjectives to provide a more descriptive and poetic touch to the phenomenon.