On Monday morning, the Bengaluru sky was lit up with a rainbow ring encircling the Sun.
https://twitter.com/AshwiniMS_TNIE/status/1396699977817018374?ref_src=twsrc%5EtfwSpectacular images of the sun went viral on social media.
https://twitter.com/AK_Aspire/status/1396715235042463745?ref_src=twsrc%5Etfw https://twitter.com/TweetsTeju/status/1396702078714609665?ref_src=twsrc%5EtfwThe phenomenon is popularly known as the 22-degree halo because the ring has a radius of approximately 22 degrees around the sun or moon.
A 22-degree halo is an optical phenomenon that belongs to the family of ice-crystal halos. The halo of the sun or occasionally the Moon (also called a moon ring or winter halo), occurs when the sun’s or moon’s rays get deflected/ refracted through the hexagonal ice crystals present in cirrus clouds. These clouds contain millions of tiny ice crystals, which refract, split and even reflect 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, in order for the halo to appear.
Another phenomenon that results in the formation of a ring around the Sun or Moon—and therefore sometimes confused with the 22-degree halo—is the corona. Unlike the 22-degree halo, however, it is produced by water droplets instead of ice crystals and it is much smaller and more colourful.
While it may appear as a rare cosmic occurrence, a cursory Google search will reveal that halos are common phenomenons that are spotted regularly across the world. Though their occurrence is more common in cold countries, it is rare and unpredictable in India because of being a tropical country.