Hurricanes

Hurricanes are the most destructive natural disaster; they are very powerful and violent storms, often associated with strong winds and heavy rains. A storm is classified as a hurricane when the speed of wind reaches 74 miles (119 kilometers) per hour. Hurricane storms usually start over warm sea (near the equator) and are accompanied by fierce winds, flash floods, mudslides and huge waves. A powerful hurricane can kill more people and destroy more property than any other natural disaster.

Hurricanes are given a different label, depending on where they occur. If they begin over the North Atlantic Ocean, the Caribbean Sea, the Gulf of Mexico, or the Northeast Pacific Ocean, they are called hurricanes. Like storms that occur in the Northwest Pacific Ocean west of the imaginary International Date Line are called typhoons. Near Australia and in the Indian Ocean, they are referred to as tropical cyclones.

[edit] Causes of Hurricanes

Hurricanes can develop when the sun’s rays heat tropical waters to at least 82 degrees Fahrenheit. This causes the air to grow warmer and rise. Water rises with it as vapor, and the heat causes the air to rise faster and faster. In about 12 hours, the heated air will begin to circle counterclockwise, forming stronger and stronger winds that whirl with increasing speed. Air that is motionless is calm. When it moves slowly, it is a light breeze. If it moves slightly faster, it becomes a fresh breeze, and even faster is a high wind. A wind becomes a hurricane when it reaches speeds of more than 74 miles (120 km) per hour. It is unknown what top hurricane speeds are, because instruments have always been destroyed by high winds or flying debris. Some estimate that hurricane winds do not surpass 250 miles (400 km) per hour, while others say they can reach 600 miles (960 km) per hour.

The moist, hot winds of a hurricane swirl upward around a calm column of low-pressure air known as the eye. Some hurricanes can develop more than one eye, but the largest is always the main eye and measures an average of 15 miles across. Inside the eye there are no storm clouds, almost no wind, and calm conditions. However, beneath this tranquil center is wild, stormy chaos.

The rising winds rotate in increasingly tight spirals around the eye, rising faster and faster. Cooler air is also sucked in, heated, and sent twisting up the eye. When the hot air rises high enough, it cools and forms water droplets that cluster together as clouds and drop rain. The rain is blown around by fierce winds.

Hurricanes were once thought to be shaped like doughnuts, circling around the eye. However, satellite images have shown them more to resemble pinwheels, with thicker clouds near the center and long, thin, trailing ends.

The atmospheric pressure is lowest closest to the eye, making the winds there spin faster. At the storm’s outer edges, they blow more slowly. A hurricane moves west or northwest at an average of ten miles an hour, with a wind radius as large as 100 miles. As it moves, it churns up the sea beneath the eye, sucking ocean water up and creating huge ocean waves. The raised water is carried along by the storm to the shore.

[edit] Effects of Hurricanes

When a powerful hurricane hits land, it can cause more damage to life and property than any other natural disaster. The effects of hurricanes include storm surge, strong wind, inland flooding and tornadoes.

• Storm surge is the most devastating effect that accounts for 90 percent of the hurricane deaths. It refers to the rapid rise in the level of water that comes ashore, as the hurricane hits land.

• The overall effect of a hurricane depends on speed of the wind. It helps to determine the force of the hurricane storm, the storm surge and the damage that the storm can cause.

• It is a fact that inland flooding causes more deaths than the actual hurricane storms. On an average, 5-10 inch rainfall is common. However, rainfall may increase depending upon the storm.

• Hurricane storms may also result in tornadoes. However, the frequency and occurrence vary from one hurricane storm to another. Very often, such tornadoes are of minimal strength.

[edit] Global Warming Affects Ocean Temperatures

As more and more greenhouse gasses and other global warming factors make the planet warmer, summertime ocean temperatures edge to increasingly higher numbers. As the global-warming-induced warm water reaches critical temperatures of 80 degrees F, the environmental phenomenon can directly contribute to the formation of hurricanes. As already warm tropical waters become even hotter due to the effects of global warming, storms become more and more intense and can produce disastrous effects when they encounter land.