Current events often deal about natural disasters. Worldwide, many natural catastrophes happen every year: tornadoes, thunderstorms, floods, hail, drought, fire, seism, volcano activity. Theirs effects often are dramatic. Lately, we heard about the tsunami in Asia, and also about the seism in Pakistan. These phenomena were murderous. A hurricane is one of the most spectacular and powerful of weather systems. As is shown in the histogram at the top, a windstorm is also one of the most frequent of natural disasters, with 121 occurrences in 2004. First, I will introduce the different terms for hurricanes and theirs categories. Then, I will explain when, and where, hurricanes form. Besides, I will explain the formation and the structure of a hurricane. At last, I will quote the effects. Hurricanes are classified by form and intensity. A tropical depression is constituted of clouds and thunderstorms with surface winds of less than 63 kilometers per hour.
[...] The map on the left shows hurricane activity between 1903 and 1925, and between 1971 and 1994. The map on the left shows hurricane activity during the two others periods. By comparing the two documents at the top, we can see the increase of temperatures lead to an increase of hurricane activity. The next factors required is a quick decrease of temperatures with height and the mid-troposphere must be relatively moist. The troposphere starts at the earth's surface and extends to an altitude from 8 to 15 kilometers. [...]
[...] hurricanes with winds exceeding 119 kilometers per hour are ranked in five categories. WHEN ? WHERE ? 1 Hurricane seasons We can see from the table, most of the time, hurricanes happen in late summer, when water temperatures are warmest, but they may develop anytime in accordance with the region. Hurricane places Normally, hurricanes form within 30 degrees of the equator and form within 20 degrees. However, they never form within 10 degrees because the Coriolis effects is too weak. [...]
[...] CONCLUSION Hurricanes are hard to observe and to anticipate. If a cyclone forms between 3000 and 5000 km of a coastline, it will arrive five or six days after. However, if it forms between 500 and 600 km, it will arrive in less than one day. As many natural disasters, hurricanes are more and more frequent. There were 12 hurricanes this year. That is exceptional. Moreover, Katrina, Rita and Wilma are most powerful hurricanes ever recorded in Atlantic. As is show in the histogram, natural disasters soar. [...]
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