(Photo from http://www.atoptics.co.uk/. Check out this site–lovely pictures and descriptions of wondrous atmospheric phenomena.)
Once again, Blue Ridge Blue Collar Man and I were talking at supper, when he told me about another wonder one of his co-workers had seen. (There are many advantages to working outside!) A few weeks ago, it was a huge cloud of dragonflies. This time, it was an upside down rainbow.
“An upside down rainbow?” I said.
“Yeah,” said Tom. “He got a picture with his cell phone. I saw it, but it was so blurry, you couldn’t really see much. “
I smirked. “Oh, sure. And I suppose he also got a shot of Bigfoot walking underneath? But it’s blurry, right?”
But I decided to check it out anyway. So I googled “upside down rainbow.” And, to my surprise, there is such a thing. Except that it’s not really a rainbow. It’s called a circumzenithal arc. And, though it is rare here, it is supposedly more common than rainbows in the far north.
Longtime readers may remember my post on sundogs. Well, circumzenithal arcs are the result of the same phenomenon—sunlight refracting off the hexagonal ice crystals in cirrus clouds, usually late in the day when the sun is low, especially when it is cold. The position of the colors in a circumzenithal arc is opposite that of a rainbow, with the red at the bottom and the blue and violet on top.
So, my apologies to Tom’s co-worker for my skepticism. He was fortunate indeed to see such a rare sight. I have definitely put circumzenithal arcs on my list of sights I want to see before I die. How lovely to see the sky smiling.