greenflash sun
© Thom Peck
The Sun setting, but above true horizon due to the hills between us and the Pacific 20 mile away. The incoming marine layer doing some optical aid, I suspect. The green flash was not naked eye, or at least we didnt see it.
Canon t6i at f/13, 1/2000 second 250mm, ISO 200
For seaside photographers, nothing beats a green flash--that sudden pulse of verdant light at sunset as the sun vanishes beneath the ocean waves. Thom Peck of Poway CA was near the Pacific Ocean on May 4th when he captured a green flash. But it didn't come from the ocean waves. It came from the top of a cloud:

This is a rare 'cloud-top' green flash, sometimes seen as the sun's rays graze a distant cloud bank. They are not well understood. Ordinary green flashes require a temperature inversion layer near the sea surface. Similar inversions may sometimes occur at the top of marine stratus clouds.

"The green flash was not naked eye--or at least we didn't see it," says Peck. "But we photographed it easily enough using my Canon T6i digital camera." Photo settings may be found here.

greenflash rare cloud