Fire Rainbows, Idaho
Also called ice halos, these vivid rainbows are typically seen just beneath the sun or moon. They are created by light shining through atmospheric ice crystals, and only at certain latitudes can be seen. The clouds have to be at least 20 thousand feet in the air, with the correct number of ice crystals and the sun has to strike the clouds at precisely 58 degrees.
In general, a “fire rainbow” appears when the sun is high in the sky, higher than 58° above the horizon, and the light passes through translucent. Sunlight infiltrating the crystals’ vertical side and leaving through their bottom side is refracted through a prism and separated into an arrangement of visible colors. When the plate crystals in cirrus clouds line up with their sides parallel to the ground, the result is a brilliant spectrum of colors resembling a rainbow.
The Devil is in the details…..