【原】Hurricanes ( August 17：美国历史上的今天 )

内容提要：Hurricanes，即飓风，是一种在大西洋地区产生的强大热带气旋。它的等级由一到五不等，风速、破化力随着等级递增。

Hurricanes are violent windstorms暴风 with a circular movement that carry with them huge amounts of rain. They cause more damage than all other kinds of storms. They form in the warm water areas of the Atlantic Ocean. 

A hurricane begins in a low pressure area over warm water. Air is pulled inward by the low pressure. Wind begins to rotate旋转  counterclockwise逆时针. As pressure drops near the center, wind speed increases. It pulls moist潮湿的 air from the ocean's surface.  The moist air spirals盘旋 upward in the center. The air cools and rainstorms form. This pattern continues as the storm feeds on itself, growing stronger and higher. When the wind speed is greater than 73 m.p.h., it is a hurricane. A column of calm, warm, cloudless air forms in the center. It is the eye of the storm. 

A hurricane can become 10 miles high and 200 miles wide. It travels across the ocean at various speeds. It might change direction several times. That is why it is hard to know when and where it will strike land. It weakens rapidly as it passes over land. 

Hurricanes are rated定级 by categories, depending on their wind speeds. Category种类 Ⅰ means winds are 74-95 m.p.h. The highest category is 5. This means the winds are moving faster than 155 m.p.h. The higher the category, the more damage it causes. 

Hurricanes are given names so weather people can tell them apart when there are more than one over the ocean. On August 17, 1969, Hurricane Camille struck Mississippi and Louisiana. It was a category 5. It caused millions of dollars in damage and 256 people died.

本文内容选自上海外语教育出版社引进出版的《听读美国小故事》第8册（8月）。如需购买，可到当当、亚马逊、京东等网上书城去看看。