A
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 sucked 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 icestones 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 pennysized hail can cause light damage to trees and vegetation and possibly cause minor injuries to people and animals. Tennis ball to baseballsized hail is obviously damaging. It can cause severe damage to crops and produce lifethreatening 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 softballsized 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.
21.What makes some hail contain something unusual?
A.Air currents.
B.Strong storms.
C.Thunderstorms and tornadoes.
D.Tornadoes and updraft currents.
22.What does Paragraph 2 mainly tell us?
A.How hail comes into being.
B.What graupel is made up of.
C.What different layers of hail look like.
D.How graupel mixes with water and ice.
23.What's the purpose of the last paragraph?
A.To urge people to stay away from hailstorms.
B.To warn drivers of the potential dangers during hailstorms.
C.To offer guidance to drivers on how to prevent hail damage.
D.To advise people to purchase necessary protective equipment.
