Is a Rainbow Iridescent?

A rainbow cloud can occur because of something called cloud iridescence. It usually happens in altocumulus, cirrocumulus, lenticular and cirrus clouds. Iridescent clouds happen because of diffraction – a phenomenon that occurs when small water droplets or small ice crystals scatter the sun's light.

What are iridescent clouds called?

Iridescent clouds, known as "fire rainbows" or "rainbow clouds," occur when sunlight diffracts off water droplets in the atmosphere. And the recipe for these heavenly sights is actually pretty simple. Like common cloud-to-ground rainbows, iridescent clouds usually accompany thunderstorms.

Is the sun iridescent?

For a circumhorizon arc to occur, the sun must be high up, over 58 degrees above the horizon. Iridescence usually occurs close to the sun, which makes it difficult to photograph. You need to hide the sun so that sunlight does not overwhelm the colors in the cloud. This is an iridescent cloud.