作者:深圳教育在线 来源:szedu.net 更新日期：2008-2-4
Hurricanes (龙卷风)
Did you know that before 1950, hurricanes had no names? They were simply given numbers. The first names were simply Alpha, Bravo, Charlie, etc. but in 1953, females names were given because of the unpredictability (不可预知) factor of the storms. In 1979, realizing the sexist (性别歧视的) nature of such names, the lists were expanded to include both men and women.
Hurricanes and typhoons (台风) are the same things. If they form in the Atlantic, we call these strong storms hurricanes, from the West Indian word hurricane, meaning "big wind." And if they are Pacific storms, they are called typhoons from the Chinese taifun, meaning " great wind." To be classified as a hurricane, the storm must have maximum winds of at least 75 mph. These storms are big, many hundreds of miles in diameter.
Hurricanes get their power from water vapor as it gives out its stored-up energy. All water vapor gives out heat as it condenses (凝结) from a gaseous state to a liquid state over fixed points on the equator (赤道). To make a hurricane, you must have extremely wet, warm air, the kind of air that can only be found in tropical region.
Scientists have determined that the heat given out in the process of water condensation can be as high as 95 billion kilowatts per hour. In just one day alone, the storm can produce more energy than many industrialized nations need in an entire year! The problem is that we don't know how to make sure such great energy work for us.
Predicting the path of a hurricane is one of the most difficult tasks for forecasters. It moves at a typical speed of 15 mph. But not always. Some storms may race at twice this speed, then suddenly stop and remain in the same location for several days. It can be maddening (发疯的) if you live in a coastal area that may be hit.
The biggest advance in early detection is continuous watch from weather satellites. With these, we can see the storms form and track them fully, from birth to death. While they can still kill people and destroy property, hurricanes will never surprise any nation again.
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