This hailstone, which measures 7 inches in diameter and has a nearly 19-inch circumference, fell in Nebraska on June 22, 2003. It is the largest hailstone ever discovered in the United States.
Hailstones are produced by severe summer thunderstorms, when frozen water droplets are tossed within a cloud and accumulate bulk until they're too heavy for the updrafts to support. They can cause serious damage to crops and property. Many efforts have been made to ward off hailstorms--in medieval Europe people rang church bells and fired cannons, and in the 20th century scientists tried cloud seeding--but nothing has been proven to work.