Green/purple flash

I do not recall when or where I first learned of the Green Flash but I have been fascinated with this sunset phenomenon for many years. 

What is the Green Flash?

On clear days at sunset (& sunrise as well I presume, though I have not witnessed one at sunrise) with a view to the west over an ocean, just as the top edge of the sun is disappearing below the horizon, it will turn green or even emanate a flash of green light.

I have observed the green flash from several places on the west coast of the USA and seen it from Key West & Hawaii. It’s real and caused by refraction of the last visible rays of the sun passing through the atmosphere before the sun completely disappears or sets. The atmosphere acts as a prism and causes this event. A green rim is present at many sunsets but is often too thin to be seen with the naked eye. Infrequently this green rim turns into a flash.

We have seen it several times from our home in Pacific Beach, CA.

I also witnessed a purple flash following a green flash during particularly vivid event from the coast of Fort Bragg, CA with friend Ted Chandick. The purple flash has been documented by others.