Green Ray....Also known as the Green Flash. This occurs very briefly before total sunset and after sunrise. It appears as a green flash above the sun that lasts very briefly, generally only a few moments. It is caused by refraction of light in the atmosphere.
Green Flash: Blink and you'll miss it! The last instant before the sun sets in right conditions the sun light turns into a green flash. Happens when sunset is on a water horizon. Seen a lot from California beaches sunsets.