Mila Zinkova of San Francisco who took this picture of the setting sun on Dec. 29, 2006
You have probably heard something about green flashes, but may not have seen one. If so, you’ll be happy to find that a number of pictures of green flashes are available on the Web like the one above. The one pictured above is special because its a TRIPLE green flash which is exceedingly rare. Its explanation lies in refraction of light (as in a prism) in the atmosphere and is enhanced by layered atmospheric inversions and possibly fog.
There was a time when green flashes were thought to be fables. Jules Verne, of all people, fixed them as real in his 1882 novel “Le Rayon Vert” (The Green Ray). He described “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.”
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.
For an explanation along with some great pictures of the atmospheric optics involved in green flashes and other sorts of colorful atmospheric phenonmena, I recommend this website in the UK: http://www.atoptics.co.uk/