What are sun and moon halos?

Posted by Anita Froneman on 11 January 2021

Have you ever witnessed a large glowing ring of light around the sun or moon? You’ve seen a halo in action. That’s when the sun or moon refracts light as a result of tiny ice crystals in the clouds, making its rays change direction when it enters the crystals at an angle.

There are two different types of halos, namely those formed by low-level diamond dust during very cold weather, and those halos formed by ice crystals in high cirrus clouds, according to Earth Sky. Cirrus clouds are thin clouds as high as 20,000 feet from the Earth.

These rings have a radius of approximately 22 degrees around the sun or moon, leading to some experts also referring to them as ’22-degree rings’. Different colours within the halo can sometimes be seen due to the prism-effect of light passing through the ice crystals, creating a beautifully mesmerising effect.

Legend has it that when you see a halo around the moon or sun, dramatic rain is soon to follow.

Halos can occur anywhere on the planet during winter or summer, and a lucky South African recently witnessed a halo around the sun in Pongola, KwaZulu-Natal.  Sfiso GamRoji Nkonyane captured this perfect circle in the clouds on January 8.

Picture: Sfiso GamRoji Nkonyane

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