'Fire rainbows' are a rare phenomenon that only occur when the Sun is higher than 58° above the horizon and its light passes through cirrus clouds made of ice crystals.
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 .
