On the drive home from my sister-in-law's house on Christmas Day I saw a phenomenon that was new to me. The cirrus cloud in the sunny sky looked like it had a piece of rainbow in it. This was an iridescent cloud where the ice crystals in the sky around and in the cloud diffract the light into a prism. It stayed that way for at least 10 minutes.
This afternoon coming home from the restaurant, I saw another cloud with irisation. In this one the colors were fainter and softer. I think a bigger cloud near it also had a little bit of color at the edge, but again not as distinct as the Christmas Day phenomenon.
