Short Stories for Teachers
A hurricane is a naturally-occurring violent tropical storm characterized by spiraling winds of high speed and great destructive power. The diameter of the wind spiral may reach into several hundred miles. Hurricanes develop from large warm bodies of water and then move towards land at a speed of ten to thirty miles per hour. Hurricanes can produce torrential rainfalls, high waves and storm surges.
The term hurricane is used for tropical storm that occurs in North Atlantic and Northeast Pacific. Elsewhere the terms used are typhoons (Northwest Pacific) or cyclone (Indian Ocean). The term hurricane is derived from the Caribbean Amerindian word for storm god called "Huracan."
Hurricane season usually occurs from July to November peaking around August to September.
A hurricanes is formed when warm air that is over the ocean surface evaporates into the atmosphere due to solar heating and is replaced by colder, denser air rushing inwards towards the eye and then spiraling upwards around it. This becomes a low pressure area. A hurricane's chief energy source is the discharge of the heat of condensation from water vapors that are condensing at higher altitude. The eye is usually circular and may range from 1.9 miles (3 km) to 230 miles (379 km) in diameter. Winds usually develops around the eye.
When the maximum sustained wind reaches 33 miles/ hour (54 km/h) it is called a tropical depression. A tropical storm develops when the maximum sustained wind is between 35 to 63 miles/hour (56-102 km/h). It becomes a hurricane once the maximum sustained wind is between 64 miles/hour (104 km/h)and 140 miles per hour (220km/h).
There are several factors that affect the formation of a hurricane. One is the water temperature of the Atlantic Ocean's surface. A water temperature of not less than 26.5 degrees Celsius (79.7 degrees Fahrenheit) to a depth of not less than 50 meters (160 feet) is needed to cause the atmosphere to be unstable and create convection and thunderstorms. Another factor is the fast cooling as the water vapor goes up. High humidity in the troposphere is also needed since large amounts of moisture in the air are favorable for the formation of the weather disturbance.
Wind shear should not be low because a high wind shear is not favorable to the circulation of the storm. The storm should form at least 555 km (345 miles) away from the earth's equator so that winds blowing towards the center of the low pressure are is deflected by the Coriolis effect thus creating circulation. Finally, a pre-existing system of weather disturbance should be present.
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