This evening, Valentine's Day, I saw the setting sun exhibit a fairly common, but rarely noticed, "green flash" at the moment the edge of the sun goes below the horizon. (It's rarely if ever visible except over the ocean.) For the first time ever I got a picture of it. The sunset was at 5:37 pm. Here are three photos in succession. The first is a moment before the sun disappeared.
The second, showing the distinct green flash, was about 4 seconds later. (You can see that it's a little greenish compared with the red-orange of the previous image. To capture the bright green that can be seen with the unaided eye -- and which lasts about a second -- would require getting the exposure exactly right.)
On the third image, about 4 seconds later, it's all gone.
The green flash is caused by the prism-like refraction of the atmosphere under certain conditions. NASA's Astronomy Picture of the Day has a good explanation of it.
YouTube has quite a few videos purporting to show the green flash, but this is the only one in which I can see it. It's at 37 seconds.
You might be able to glimpse it on this one about 2 seconds before the end -- or it might be wishful thinking. At any rate, the voice-over narration provides a good explanation.
Anybody else else have experience with the green flash at sunset (or sunrise!), or maybe pictures? Let us know -- post a comment.
Green may not be the best color to end St. Valentine's Day, but St. Paddy's Day is just around the corner.
Very cool You Tube videos of the green flash. No wishful thinking there. I saw them in both videos. That's the closest I've come to seeing the phenomenon, as I'm usually not in a spot to see the setting sun.
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