Hail Stone Formation

Partha · Subject: Hail Stone Formation Wed Mar 26, 2008 11:10 am

HOW ARE HAIL STONES FORMED?

A clue to the formation of hailstones is seen when a hailstone is cut in half. Most show an onion-like layering of alternating clear and opaque ice. This layering demonstrates that the stone is built up by coatings of ice successively frozen onto the surface of the hailstone. Each coating evidences a buildup in an environment different from that in which the coat below formed. Clear ice forms in the part of the cloud where water is copious; ice with many trapped air bubbles, hence opaque, forms in drier portions. When we cut the hail stones into half, then it is common to find out the irregular shaping of the inner components just like the Marble.
Important to the buildup of hailstones is the existence in thunderhead clouds of super cooled water: water that remains in liquid form well below normal freezing temperature. Super cooled water droplets colliding with a foreign object a piece of dirt, an embryonic hailstone--will freeze to it and thereby increase its size.
In the north, large hailstones are rare because the lack of strong ground surface heating does not favor the buildup of the gigantic thunderstorms common in some temperate climates. There was an incidence of falling of a hailstone which was 15cm in diameter that is 5 1/2 inches and 1.58 pounds in weight in Potterneb on 7th July 1928. History says that a hailstorm has claimed about 246 lives in Uttar Pradesh in India.