The (Illusive) Green Flash

As the bottom edge of the sun touches the horizon and begins to disappear, the upper tip of the sun turns a brilliant green - for just an instant.

Conditions must be just right for the green flash to occur:

1) You must have a completely unobstructed view of the horizon
2) There cannot be any fog, haze or clouds.

If you can see the bottom edge of the sun touch the sea, you may see the green flash.

Constantly look away from the sun to avoid visual fatigue and glare. After a 7/8th decent, you may see the sun glow emerald green. Although it's not a flash per se, it is very brief in duration.

Just as the sun sets, green light is bent - running parallel to the earth's surface. The other colors are either absorbed or bent.

The green flash is best seen from a ship at sea.