英语听力：自然百科 飓风揭秘（在线收听） |
An Atlantic hurricane often begins its life over the mountains in East Africa as an area of low pressure. It travels across the Sahara Desert, then moves out over warm ocean waters. Travelling with the trade winds and circles the globe just above and below the equator, these lows can spawn thunderstorms over a broad region. They gradually come under the influence of the earth rotation called the Coriolis Force and begin to spin. Satellites orbiting the globe begin to peer into them to watch for signs of intensification, at the center, a region of low atmospheric pressure forms, known as "the eye." It acts like a partial vacuum causing winds at the sea surface to spiral inward toward it. These in-spiraling winds evaporate moisture from the warm ocean surface. As they near "the Eye," they rise rapidly, producing clouds and rain. Much of the air flows outward at the top of the storm like a chimney; soon flows back down into "the eye" itself causing the central zone to dry out and become clear. The path a hurricane takes is determined by its interaction with weather systems and global air currents. Scientists use super computers to try to predict not only where they will go but also how they will behave along the way. Based on these predictions, alerts go out to shipping concerns, coastal business, governments and the public at large. Over the years, meteorologists have improved their forecasts of the twists and turns of a hurricane's path.
But at the same time, our exposure to these great storms keeps rising. From the coastlines of China, the Philippines and Japan to the Gulf of Mexico and the Bay of Bengal, coastal populations are growing faster than any where else in the world. Not only are there more people near the ocean, it takes more time to evacuate them all.
Scientists have been computing the risks and running the probabilities of a terrible growing conflict between humans and the nature. To reduce the margin of error, hurricane scientists will have to improve their ability to predict a storm's intensity as it makes its way toward land, whether it will fizzle, bring in only wind and high surf or become a destructive monster. |
| 原文地址：http://www.tingroom.com/lesson/zrbaike/2010/259083.html |