Dear Hank,

Re: The Blue Flash

November 16, 2011

I don’t remember exactly when it was, about a week or two ago, we were waiting for sunset. When it’s clear enough we especially like to watch because we like to watch “The Green Flash.” This is an optical effect cause by the bending of light at sunset just like a prism can bend light and break it out into the different colors of the spectrum. Typically, you see the red end of the spectrum; but, if you watch the last place where the sun appears to be in contact with the horizon, at that tangent point, you will typically see a brief spot of green light. This is because the Earth is blocking the Sun’s red rays and thus the next part of the spectrum will be visible. On some evenings the green will appear as a small circle and will close down to nothing in a few seconds. Sometimes you’ll even see a purple tinges around the green and as the green circle gets smaller and smaller you’ll see a small purple circle, a “Purple Flash.”

On this evening the sunset and we watched the tangent point. It went green then it went a deep blue in a perfect circle., blue, like the top end of a crayon. If you remember your color spectrum It goes: red, orange, yellow, green, blue, purple.

I’ve seen the green flash with tinges of yellow and then purple but the blue usually gets lost. But on this evening it didn’t get lost. It stood out big and bold. Why? There was a low layer of clouds. Typically, if there are clouds or if the horizon is ragged you won’t see any flash. On this evening I have to conclude that the low layer of clouds blocked the purple light and let the blue shim through, and what a blue it was! The kind of thing I can see over and over in my mind.

Gotta go, stay safe,

Bryce