Thanks, Joybell, for sharing your experience. Didn't know they existed. I'll be keeping my eyes open for them now.

Atmoshperic optical phenomona are amazing and pretty special experiences. I've looked often for the green flash at sunset over the ocean but have never seen it. Rainbows--many here in western Oregon; auroras--a few faint ones.

But once at the summit of a high hill, with dense clouds a few meters away on one side and the sun on the other, I saw a "rainbow" encircling the shadow of my head in the cloud! All the colors in a circle starting from the edge of the shadow of my head and broken only by the shadow of my neck. I understand that mountaineers have a name for it, but I've forgotten it.

An awe-inspiring sight!

David