Submitted by : Morah Yehudis for our pleasure and wonder. From Snopes.com : This is a real photograph of an atmospheric phenomenon known as a circumhorizontal arc, the example shown above was captured on camera as it hung for about an hour across a several-hundred square mile area of sky above northern Idaho (near the Washington border) on 3 June 2006. In general, a circumhorizontal arc (or “fire rainbow”) appears when the sun is high in the sky (i.e., higher than 58° above the horizon), and its light passes through diaphanous, high-altitude cirrus clouds made up of hexagonal plate crystals. Sunlight entering the crystals’ vertical side faces and leaving through their bottom faces is refracted (as through a prism) and separated into an array of visible colors. When the plate crystals in cirrus clouds are aligned optimally (i.e., with their faces parallel to the ground), the resulting display is a brilliant spectrum of colors reminiscent of a rainbow. Check out this website for more science of the phenomena : Atmospheric Optics : See a larger photo of another Circumhorizontal Arc and an explanation of Cloud Ice Crystals

 

Last modified: 9:17 PM 3/16/2008