What is the Sun Halo?

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About Sun halo:

What is it? It is an optical phenomenon that occurs due to sunlight refracting millions of hexagonal ice crystals suspended in the atmosphere.
How it is formed?
- When white light passes through unique hexagonal ice crystals found in upper-level cirrus clouds, causing the halo to have colours.
- The clouds contain millions of tiny ice crystals, which refract and split the light to give an impression of a circular rainbow ring.
- The crystals have to be oriented and positioned just so with respect to your eye, for the halo to appear.
- Light undergoes two refractions as it passes through the ice crystals and the bending that occurs depends on the ice crystal’s diameter.
- The two refractions bend the light by 22 degrees from its original point, producing a ring of light around the Sun or the Moon.
The lunar halos are mostly colourless as moonlight is not very bright.
In the case of the Sun, these colours are more noticeable and appear as bright as a rainbow.

Q1) What are Cirrus clouds?

Cirrus clouds are a type of high-altitude cloud that are composed of ice crystals. They are thin, wispy, and often appear as long, white, feather-like clouds, stretched out across the sky. Cirrus clouds form at altitudes of 16,500 to 45,000 feet (5 to 13 kilometers) and are usually associated with fair weather.

Source: Sun halo spotted in Prayagraj leaves many awe-inspired. Here’s what it is