Thanks to Gary Sullivan for these images… he writes:
“Attached are some interesting pictures of a cloud with rainbow or northern light like colors. I took them at 5:30 from Northport 30 July 2008. Is it the sun reflecting on ice or water in the cloud?”
The technical name for this is a circumhorizontal arc (CHA). It is a halo or an optical phenomenon similar in appearance to a horizontal rainbow, but in contrast caused by the refraction of light through the ice crystals in cirrus clouds. It occurs only when the sun is high in the sky, at least 58 degrees above the horizon, and can only occur in the presences of cirrus clouds.
