The Mystery of the Green Flash at Sunrise and Sunset.

The green flash is a rare phenomenon that occurs during sunset or sunrise when the atmosphere behaves like a prism, separating the stack of different-colored images of the sun. The green color is produced by atmospheric refraction of light, causing objects near the horizon to appear slightly higher in the sky than they really are. The green flash can be elusive, but it can be seen during very clear and exceptionally transparent skies. To catch a glimpse of the green flash, look for a distant, sharply-defined, and low horizon, and avoid looking at the sun until the last moment to avoid eye damage.