Kolkata sun halo
© Indian Express/Subham Dutta22 degree Halo — a ring of light around the sun on Saturday on Kolkata sky.
The phenomenon was observed between 12.10 pm and 12.40 pm when the fifth and penultimate phase of Assembly elections was underway in parts of the city

A red and blue ring around the sun, popularly known as '22 degree circular halo' was sighted this afternoon in the city.

The phenomenon was observed between 12.10 pm and 12.40 pm when the fifth and penultimate phase of Assembly elections was underway in parts of the city.

The phenomenon popularly known as the 22 degree circular 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, a senior researcher with the MP Birla Planetarium told.

"These kind of cirrus clouds are generally formed when water vapour freezes into ice crystals at altitudes five to ten kilometres above the earth's surface," the researcher said.

"It's a very common phenomenon in the cold countries. But in our country it's occurrence is rare and cannot be predicted... The red and blue ring around the sun was seen for around 30 minutes," he added.
Kolkata sun halo
© Saurabh Roy

The 22 degree halo was last observed in April 2013 in the suburbs of the city, the meteorologist said, adding, the phenomenon takes place before an impending storm.

Source: Press Trust of India