We all are accustomed to watching rainbows in the sky. We've seen the pretty images of nature in all its glory and we've decoded the physics behind it as well. But there's another rare natural phenomenon that most of us are unaware of and it's called the 'Fire Rainbow'.

A Circumhorizontal Arc (popularly referred to as a Fire Rainbow), is an optical phenomenon where an ice-halo is formed by the refraction of sun-rays or moonlight in plate-shaped ice crystals suspended in the atmosphere.

Source: National Geographic

Fire rainbows are a combination of clouds and rainbows, with the brilliant colours of a rainbow conforming to the contours of a cloud. 

The science behind this mystical phenomenon is rather simple. The halo is formed by sunlight entering horizontally-oriented hexagon ice crystals through a vertical side face and leaving through the near horizontal bottom face. This refraction leads to the formation of the rainbow.

The clouds are made of ice-crystals and the texture of these clouds make it seem like certain sections of the sky are on fire.

Source: Amusing Planet

It's sad how this spectacular event of nature lasts for a short time and is a rare sight as all the necessary factors need to be available at the correct time and at the correct position. You can't see this phenomenon if you're too far north or south and they can only be formed during certain days of the year.

Source: Flickr

This cool work of nature definitely gives 'being lit' a new meaning.