Most Beautiful Fire Rainbow | Colorful Rainbow Cloud -- Circumhorizontal arc
Technically called a circumhorizontal arc, fire rainbows are caused by light passing through wispy, high-altitude cirrus clouds. This one was seen over South Carolina Monday for about an hour. It was photographed and uploaded to Amazing Cool Pictures.
Fire rainbows occur only when the sun is very high in the sky (more than 58° above the horizon). What's more, the hexagonal ice crystals that make up cirrus clouds must be shaped like thick plates with their faces parallel to the ground.