Green Flash

I love watching sunsets on cruises. Sometimes if you are lucky you can catch a green flash as the sun is setting. This one I caught on the west coast of Mexico April 26, 2019.

This is the explanation from World of Phenomena:

Green Flash

Why does the top of the sun appear green? Think of the sunset and how the sun’s orange and red colors look hazy and huge as the sun appears to sink and touch the horizon. The reds of a sunset are caused by the same effect as a green flash—both are caused by refraction of light. As the sun sets, the light is viewed through a greater and greater density of molecules and the light is therefore refracted as the atmospheric soup acts as a prism spreading the rainbow of light. As the light passes through water vapor and other particles in the atmosphere this prism effect causes the sunlight to absorb and refract different wavelengths of electromagnetic energy we call colors. This explains how the oceans horizon with its thermal difference of water and air create an ideal setting for a mirage. At the last seconds of a sunset the color green in the light spectrum is refracted enough to give off the mirage of green. The green appears separate, just above the red-orange setting sunlight. This optical mirage, as seen by the human eye, is a case of looking at the right place at the right time under the right conditions. Besides being green, this explains why seeing a green flash is associated with luck!

Photo Credit: Tim Free

Click for larger image.

green flash

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2 thoughts on “Green Flash”

  1. After many years of doubting the green flash of sunset , I was privileged to view it repeatedly while cruising northwards on a ship in the South Atlantic near the tropics . I saw it clearly through my 10×42 binoculars on several occasions . (Warning : only look at the sun through binoculars at the very last minute when it is very low !!) The green flash appeared when the sun was perhaps a fraction lower than in Tim Free’s picture shown . The green colour started in the left and right (limbic ?) corners of the last of the sun and quickly spread over the whole of the remaining crescent of sun from both sides , and then the sun was gone . Very brief . It was not like the thin green line at the top of the sun as in Tim’s picture . I can only describe what I saw , and have no explanation for what I saw nor why it was different from Tim’s fine picture . I observed the same thing on 3 or 4 evenings from the ship’s upper deck . I am now convinced the green flash of sunset is real ! Without the binoculars the green flash was hardly visible , if at all . Much the best through binoculars (with care !) .

  2. Thanks for your comment. I will continue to look for and photograph the green flash. I have not seen the crescent effect you’ve described. Hopefully I can capture it on camera some day. I have seen the green flash now about 3-4 times and it has always been on the top of the sun, but unless you are looking at it with binoculars or telephoto it can be hard to tell. Tim F.

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