So-called "fire rainbows" are neither on fire nor are they rainbows, but they sure are stunning.
They are technically known as iridescent clouds, a relatively rare phenomenon caused by clouds of water droplets of nearly uniform size, according to a release by NASA. These clouds diffract, or bend, light in a similar manner, which separates out light into different wavelengths, or colors.
That makes them similar to rainbow-colored glories, which are also formed by diffraction, and also produce an oscillating pattern of colors ranging from blue to green to red to purple and back to blue again.
Although iridescent clouds have rainbow-like colors, the way light is scattered to produce them is slightly different. Rainbows are formed by refraction and reflection. When light is refracted, it is bent by passing through mediums of different densities, such as water or a prism. Reflected light bounces off a surface at an angle equal to the angle it hit the surface at. Diffraction, though, involves light waves being scattered into a ring-like pattern.http://www.foxnews.com/scitech/2012/08/02/amazing-photo-fire-rainbow-over-florida/?intcmp=trending