The Green Flash is an optical phenomenon that occurs shortly after sunset or before sunrise where a green spot is visible for a second or two above the sun.  The reason for this optical phenomena lies in the refraction of light (like seen through a prism) in the atmosphere.  Light moves more slowly in lower denser air than in higher thinner air and the sunlight follows paths that curve slightly with the curvature of the earth.  The higher frequency light (green/blue) curves more than the lower frequencies (red/orange) so the green / blue rays remain visible after the red rays are blocked by the curvature of the earth.

The green flash is enhanced by a mirage and is more likely to be seen in clean clear air.  Slight magnification can be a great help.  Just look for a green rim on top of the setting sun on most clear days.   The major problem for most people is that they do not know what to look for.  Flashes are not always green; they are not a flash as in a sudden burst of light and do not usually light up the sky, but instead are often small and inconspicuous.

Now that you know what to look for, you will find that they are not as rare and elusive as most sunset watchers believe.  And remember if you don’t see one, you still witnessed one of Naples’ magnificent sunsets!