HURRICANE INFORMATION

Formation and Movement

     A hurricane is a very powerful storm with strong winds spiraling around a calm center. A hurricane is classified as a storm with wind speeds higher than 70 mph and forms over warm oceans. Most hurricanes last one week, but some can last up to several weeks and can be very destructive.
     Hurricanes must be formed over the ocean. They use the heat from the water and convert it to mechanical energy, which causes their rotation. The rotation starts when a low-pressure front from the land hits the storm from the ocean. The direction of the hurricane depends on the Coriolis effect, which is caused by the Earth�s rotation. In the northern hemisphere, hurricanes spin counter-clockwise, but in the southern hemisphere, they spin clockwise. Near the equator, there is not enough Coriolis force to start a hurricane, so there are usually no hurricanes within 500 miles of the equator.
     Hurricanes move because of steering currents, prevailing winds that move the entire hurricane, like a quickly spinning top that drifts slowly across the table. When the hurricane reaches land, it loses some pressure and energy, but then the winds can pick up and the hurricane becomes stronger again when it is completely on land. In the eye, or the center of the hurricane, it is calm, but around the eye is a cylindrical wall of clouds with the strongest winds, called the eye wall. The energy for the hurricane to keep going is gotten from water vapor that condenses into raindrops. The condensation of the water causes heat to be released, so as long as the air is warm and moist, the hurricane will have energy to keep going. Eventually, as the hurricane stays over land, it will run out of moisture and heat and the hurricane will end.

Blank Tracking Chart

For a detailed tracking map, click here.

Past Explanations of Hurricane Phenomena

     The first record of a hurricane was written in ancient Mayan hieroglyphics. The Mayan word "hurakan" is the origin for the English "hurricane". Hurakan was also the Mayan god who was said to blow his breath across the water and bring forth dry land. The Carib Indians later adopted the name Hurican for one of their gods of evil. In biblical times, hurricanes were thought of as the fury of God, able to destroy rebellious cities and nations. Some still believe this theory, although the current explanation has to do with low pressure, warm ocean, and tropical winds. Research still continues, and the theory could change at any time.

Types of Dangerous Storms

Some types of extremely dangerous storms include hurricanes and blizzards.
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