Stunning images of a rare “fire rainbow” were shared across social media last weekend in South Carolina.

The unique rainbows are formed by “light passing through wispy, high-altitude cirrus clouds," according to National Geographic.

National Geographic explained:

Fire rainbows occur only when the sun is very high in the sky (more than 58° above the horizon). What's more, the hexagonal ice crystals that make up cirrus clouds must be shaped like thick plates with their faces parallel to the ground.

When light enters through a vertical side face of such an ice crystal and leaves from the bottom face, it refracts, or bends, in the same way that light passes through a prism. If a cirrus cloud’s crystals are aligned just right, the whole section lights up in a spectrum of colors.

Check out some of the photos posted to Instagram below.

 

A photo posted by Gino (@ginknowsabe) on

 

 

A photo posted by Roger Jennings (@3rdnlong) on

 

 

A photo posted by Carole Rich Williams (@icrw70) on