Saturday, February 27, 2010

Hurricanes & Tornadoes

This table gives us information about two strong winds, hurricanes and tornadoes. Both are dangerous and destructive but there are important differences between them.

Firstly, the minimum speed of a hurricane is 74 mph, whereas that of a tornado is 40 mph. On the other hand, the maximum speed of a tornado, 250-300 mph, is higher than that of a hurricane, 155-200 mph. The hurricane is classified on the Saffir-Simpson C1-5 scale, while the tornado is measured on the Fujita F0-F5 scale. Whereas a tornado usually lasts from a few minutes to a few hours, a hurricane can last up to a week. A hurricane can be predicted 2-3 days in advance for a wide area and 6-10 hours beforehand for a locality, but a tornado can be predicted only minutes before it hits. Hurricanes start over warm oceans but tornadoes usually originate over land.

In brief, tornadoes are less predictable, last for a shorter period of time and can reach much higher wind speeds.

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