I saw one today for the first time in my life. In fact I had never even heard of it before today.
Basically it is an upsidedown rainbow, well actually just a quarter of the circle. A friend pointed it out to me in the afternoon, as the sun was quite low in the sky. It only lasted for a few minutes and then it was gone. Regretably I did not have my camera. In order for one to form, the sky has to be very clear with no rain and just very thin high wispy clouds. The rainbow colours are also reversed with violet on top and red at the bottom.
Has anyone else ever seen one of these? Apparently they are very rare in the U.K.
George
P.S. Hate to think what the pro-deluvian supporter have to say on this!