What is the Sun Halo?

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Recently, the people of Uttar Pradesh's Prayagraj were graced by an awe-inspiring phenomenon called Sun Halo.

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