Severe Weather - Hail

Hail

Any form of thunderstorm that produces precipitating hailstones is known as a hail storm. Hailstorms are generally capable of developing in any geographic area where thunderclouds (Cumulonimbus) are present, although they are most frequent in tropical and monsoon regions. The updrafts and downdrafts within cumulonimbus clouds cause water molecules to freeze and solidify, creating hailstones and other forms of solid precipitation. Due to their larger density, these hailstones become heavy enough to overcome the density of the cloud and fall towards the ground. The downdrafts in cumulonimbus clouds can also cause increases in the speed of the falling hailstones. The term "hailstorm" is usually used to describe the existence of significant quantities or size of hailstones.

Hailstones can cause serious damage, notably to automobiles, aircraft, skylights, glass-roofed structures, livestock, and crops. Rarely, massive hailstones have been known to cause concussions or fatal head trauma. Hailstorms have been the cause of costly and deadly events throughout history. One of the earliest recorded incidents occurred around the 12th century in Wellesbourne, Britain. The largest hailstone in terms of maximum circumference and length ever recorded in the United States fell in 2003 in Aurora, Nebraska, USA The hailstone had a diameter of 7 inches (18 cm) and a circumference of 18.75 inches (47.6 cm).