Described as a “multi-coloured angel hovering overhead” by some viewers, the halo-forming cloud known as a circumhorizontal arc is said to require a strict set of conditions and occur only in “high-level cirrus clouds [thin, wispy clouds] made up of tiny ice crystals”, meteorologist Justin Lock told the local news station 14 News.
“To produce the rainbow colours the sun’s rays must enter the ice crystals at a precise angle to give the prism effect of the colour spectrum” Mr Lock said. The sun must be at an altitude of at least 58 degrees above the horizon, he added.
The incredible cloud formation was observed by locals in the area including Tracey Smith, who saw it over a beach in the Isle of Palms and said it lasted for about an hour.
Rainbows are multi-coloured arcs created from the reflection, refraction and dispersion of light across water droplets. They can be seen in places where there are water droplets in the air, such as near waterfalls and lakes in forest surroundings.
SOURCE: Soo Kim