The Green Flash

The green flash phenomenon arises as by-products in astronomical refraction near the horizon, it's elusive because the atmospheric conditions required to produce the green flash don't happen that often, and require a well-layered atmosphere that allows the index of refraction to increase without interruption toward the surface of the Earth. Unfortunately, the atmosphere is usually experiencing turbulence and differing temperatures across the layers. In plain English, you need a near perfect clear horizon for the green ray phenomenon to appear. (see it better large)