Hail( 冰雹 ) is solid precipitate( 沉淀物 ) that forms within thunderstorms. Hailstones are sometimes found containing sand, leaves, nuts and insects. There are even reports of hail containing small turtles, baby crocodiles and frogs! All of them have been ed into the storm by tornadoes and subsequently enveloped in ice through repeated updraft currents( 上升气流 ). Hailstones generally begin forming as seeds of small frozen raindrops or soft ice particles known as graupel ( 雪丸 ). If graupel falls through the cloud and gets into an updraft part of a thunderstorm, it mixes with water drops and ice particles that will freeze around it as it rises, like layers of an onion. These ice-stones are carried into the tops of the cloud, gaining mass as they rise. Somewhere up there, they become too heavy for the updraft to carry and so fall towards the ground. As they fall, the outside layer melts to a clear layer. Larger hail can fall at a speed of over 100 mph, thus causing damage and injuries to almost anything. Pea to penny-sized hail can cause light damage to trees and vegetation and possibly cause minor injuries to people and animals. Tennis ball to baseball-sized hail is obviously damaging. It can cause severe damage to crops and produce life-threatening injuries to people and animals. Deaths caused by hail are rare in the US with the last known fatality occurring in March 2000 in Lake Worth, Texas. A young man died from head injuries after being stuck by a softball-sized hailstone. Deaths and injuries are more common in other parts of the world where people live in poorly constructed buildings with little protection. If caught in a hailstorm while driving, attempt to stop immediately or pull into a nearby safe place; otherwise, the effect of the hail will be maximized. Try to drive and park the vehicle in the direction of the hail so that it is hitting the front of the vehicle. Windscreens are generally strengthened and can withstand larger impacts than side and back windows. This will lessen any damage from flying glass to both people and equipment in the vehicle.