hailstones

Hail: Chunks of ice from the sky

Hailstones are balls of ice that grow as they're held up by winds, known as updrafts, that blow upwards in thunderstorms. The updrafts carry droplets of supercooled water - water at a below freezing temperature - but not yet ice. The supercooled water droplets hit the balls of ice and freeze instantly, making the hailstones grow. The faster the updraft, the bigger the stones can grow. Most hailstones are smaller in diameter than a dime, but stones weighing more than a pound have been recorded.

Details of how hailstones grow are complicated, but the results are irregular balls of ice that can be as large as baseballs, sometimes even bigger. While crops are the major victims, hail is also a hazard to vehicles and windows. Deaths are rare in the United States. The last known U.S. hail fatality was an infant killed in Fort Collins, Colo., in August 1979. Deaths and injuries are more common in other parts of the world, especially places where many people live in poorly constructed buildings. In the USA, hailstorms are most common on the Plains, especially just east of the Rockies. Other parts of the world that have damaging hailstorms include China, Russia, India and northern Italy.

Source: The USA TODAY Weather Book by Jack Williams

The heaviest hailstones on record, weighing up to 1 kg. (2.2 lb.), are reported to have killed 92 people in the Gopalganj district of Bangladesh, on April 14, 1986.

The largest hailstone ever reported in the U.S.A. weighed 1.67 lbs., was 7.5" in diameter and 17.5" in circumference. This occurred in Coffeyville, KS on September 3, 1970.