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What’s a green flash?

Those of you who like weather pictures and knowing about unusual weather phenomena probably already know what a “green flash” is, but for those who don’t, a green flash is an optical phenomenon that occurs at sunset when the setting sun may momentarily look green due to the refraction of the sun’s disk by the atmosphere.  It happens only in very specific atmospheric conditions so is very rare.  EarthSky has a good description and some fantastic pictures of green flashes in their blog post here. I’ve never seen one but hope to some day.

The elusive green flash just after sunset on July 29, 2014 in the East China Sea. Image via EarthSky Facebook friend Mike Quinn