The residents of the city of Coimbatore were on August 3, 2012 treated with a visual surprise from the sky. A rainbow like halo circle attracted thousands of spectators out of their homes and offices.
S Sanjay a keen sky watcher said, “It’s an atmospheric phenomenon which just happens, something like aalangatti mazhai (hailstorm)”. The solar halo appears when the rays of the sun reflect off the tiny ice crystals like prisms suspended in the atmosphere.
Sanjay added, “When the temperature drops in the stratosphere, the upper most layer of the atmosphere, the condensed air mass, forms ice crystals shaped like flat plates or pencils. When the sun is aligned with these crystals at a particular angle, a halo appears. It disappears as the refraction reduces.” It is also known as the kaleidoscopic effect which is a phenomenon which depends on the tilt of ice crystals in the air and the altitude of the sun.
As the crystals are large enough then a halo appears and the only significance is that it is visually brilliant. When observed closely the ring was slightly redder on the inside and bluish on the outer edges. A similar halo appeared in the year 2005 in Coimbatore.