Stages of a Hurricane：Simple Storms Grow Into Giants
A storm progresses through four different stages before it is actually considered a hurricane. First is a tropical （热带的） disturbance, which has thunderstorms and rotating （旋转的） winds. Next is a tropical depression （低气压）, which is similar to a tropical disturbance, but has winds between 23 and 39 miles per hour. A tropical storm is the next level, which has stronger wind speeds between 40 and 73 miles per hour. The wind picks up energy from the warm surface ocean water.
As a hurricane crosses over land, it begins to become weaker and reduce in strength.
At this point, a hurricane can still cause a lot of damage because of high winds, rain, and flooding, but unless it makes its way back over the open ocean, it is downgraded from a hurricane back to a tropical storm.
What's Your Name, Hurricane?
Hurricanes and tropical storms are given names to help people recognize them. Before 1953, hurricanes were not given official names. From 1953 through 1978, hurricanes were only female names like Isabel, Camille, Claudette, and Wilma. Beginning in 1979, hurricanes were given the names of both women and men. For example, in 2010, storms were named as follows：Alex （male）, Bonnie （female）, Colin （male）, Danielle （female）, Earl （male） and so on.
There are six different lists of names that change. The only way that a new name is added is adopted when a hurricane has been particularly deadly or costly and the name is retired, then replaced with a new one.
A. It is difficult to give hurricanes official names. B. And the same names are used every six years. C. During this period the hurricanes do not destroy things as usual. D. Once winds reach 74 miles per hour, the storm is officially called a hurricane. E. Scientists refer to hurricanes and storms by name as they track them across the ocean. F. This is because it's no longer over the warm ocean water where it needs for energy. G. Today, the names alternate （交替） male and female, and they are named in the order of letters. |
