What Causes the Halo Around the Sun in South Africa Today?

South African residents were treated to an amazing halo around the sun today. But what causes the ring around the sun, many asked.

Well, although the ring or sun halo is not common, it’s apparently spotted more in some countries than rainbows! The phenomenon is caused by cirrus clouds floating high above our heads (about 20,000 feet up) according to EarthSky.

A perfect sun halo in Cape Town, South Africa in October 2020. Photo: Alan Rudnicki

EarthSky says: “Halos around the sun or moon are caused by high, thin cirrus clouds drifting high above your head. Tiny ice crystals in Earth’s atmosphere create the halos. They do it by refracting and reflecting the light. Lunar halos are signs that storms are nearby.” (For more technical details, check out EarthSky.)

According to Spectrum there are millions of tiny ice crystals, and – just like with rainbows – the halo you see is personal to your view.

It’s darker in the middle – looking like a ‘hole in the sky’ – because the optical properties of the ice crystals mean no light is reflected towards the inside of the ring, explains Atoptics.

Scientists call the large circle of light a 22-degree halo because apparently the ring has a radius of about 22 degrees around the sun (or moon).

In some religious circles it’s believed that “the Sun symbolizes Jesus (Psalm 19:4-6), and the circle around it symbolizes a covenant”.