Monday, August 23, 2010

Thinking Green at Sunset

A few moments before the green flash, your basic sunset.

One of the many fun things to do in western Michigan at the end of summer, when the fish aren’t biting and birds have yet to start migration in any serious manner, is watch the phenomenal sunsets over Lake Michigan. So it was this evening, our third here. We had sore shoulders from casting to fish that had their own agenda, which did not include us. An occasional Caspian Tern would fly by and we saw two Sanderlings playing tag with the waves. So much for birding highlights.
Watching the sun set is a ritual we always participate in. Even on some cloudy evenings we sit and hope. This was about to be our third spectacular sunset and I was showing off, talking about the elusive “green flash” some people claim to see at sunset. Other than the name, I know little about this atmospheric phenomena.
Ever the optimist, I had a camera at the ready. A friend once told me I was the definition of an optimist: A guy who carries a camera when he goes fishing.
As the sun was dropping below the horizon (I know, that’s technically incorrect), we watched the fire-ball, hard to imagine it’s really 93 million miles away—give or take a few million depending on our orbit. Fully expecting the sun to disappear as it always does, just as the “red” edge sank, it turned green! To its right was a small shaft of green light as well.
Doing a bit of research, I learned this flash of green lasts only 1.4 seconds. Three of the other four people with me also saw it. That’s when I realized I had had the cognizance to keep my finger on the shutter release and blasted away at 4.5 frames per second. Thank you, Mr. Nikon.
There are pages and pages of scientific and not-so-scientific information about green flashes at sunset. Jules Verne's 1882 novel "Le Rayon Vert" (The Green Ray) popularized the green flash as: "A green which no artist could ever obtain on his palette, a green of which neither the varied tints of vegetation nor the shades of the most limpid sea could ever produce the like! If there is a green in Paradise, it cannot be but of this shade, which most surely is the true green of Hope."
Well, I have to add, in this digital age, I was unable to manipulate the color in the photos I took to match what we actually saw. Once again, Jules Verne was right.
If you want to learn more about the green flash, caused by the same atmospheric refraction and scattering effects which produce the red sunset, a good place to start is
In uniform air, the dispersion of light rays is apparently so small that the separation of red and green images is not visible. It takes more unusual layering of the atmosphere to enhance the separation.
If you have an appetite for more information about green flashes, “An introduction to Green Flashes,” by Andrew T. Young,, will give you more than you can digest in a single setting.
As Young explains, “Green flashes are real (not illusory) phenomena seen at sunrise and sunset, when some part of the Sun suddenly changes color (at sunset, from red or orange to green or blue). The word “flash” refers to the sudden appearance and brief duration of this green color, which usually lasts only a second or two at moderate latitudes. As the area that turns green is ordinarily near the limit of the eye's resolution, these are sometimes called “green dot” displays. Green flashes are by-products of the large variations in astronomical refraction near the horizon.”
And from Elton John’s, “Rocket Man,” let me steal the line, “And all this science I don’t understand.” You don’t have to understand to be amazed and enjoy.

The elusive green flash and a green “pillar” to the right.