Hurricanes are potentially deadly tropical storms. They are characterized as having high winds, more than 74 miles per hour, and areas of very heavy rainfall.
For a hurricane to form, the ocean’s water temperature has to be above 79 degrees Fahrenheit. This normally happens in the late summer and the early Fall. The wind speed needs to be above 74 miles per hour. If the wind speed is lower than that, the storm is called a tropical storm, not a hurricane.
Hurricanes start as tropical storms that form over the oceans near the equator. The warm water evaporates and rises until there are huge amounts of this moist, heated air high in the atmosphere. The air twists as it rises, turning counterclockwise north of the equator and clockwise south of the equator. As the wind speed grows faster, a tropical storm grows into a hurricane. As long as the hurricane stays over water that has a temperature of at least 79 degrees Fahrenheit or warmer, the hurricane will continue to grow in size and force as it continues to pull moisture up from the surface of the Earth.
The center of a hurricane, the eye, is very calm and peaceful. It can be anywhere from 10 to 30 miles wide, has calm winds, clear skies and warm temperatures. Directly around the eye, the winds can be blowing at speeds of up to almost 200 miles per hour. A hurricane has so much energy that if only a small portion of it could be harnessed, it could supply the United States with all of the power, heating, and fuel needs for a whole year. To make that easier to understand; it takes 500 trillion horsepower to send the wild whirling at the speed it reaches just outside the eye of the hurricane, that is the equivalent of an atomic bomb exploding once every ten seconds.
Hurricanes are rated and categorized by their wind speed. The faster the wind speed in the hurricane, the higher it is, the higher the hurricane is categorized. Hurricanes are generally stronger and more destructive during the late summer and early fall months.
Hurricanes can cause damage, not only because of the wind, but also the rain that can cause flooding, and the tornadoes that they can produce. Because a hurricane can have smaller wind speeds and still be very destructive, or have high wind speeds and cause relatively small amounts of damage, a system called the Saffir-Simpson hurricane intensity category system was developed in the 1970s to determine the destructive potential of a hurricane. This system measures the wind speed, central storm pressure, the storm-surge height, and the coastal destruction potential. With this system, there are 5 intensity levels that a hurricane can reach.
Using this system, a Category 5 hurricane is rare. Hurricane Gilbert, which hit Jamaica and the Yucatan Peninsula in 1988, and Hurricane Andrew are were both Category 5 hurricanes. Hurricane Hugo, which hit land in Charleston, South Carolina, was only a Category 4 hurricane using this system. All of these hurricanes caused death and destruction. Having this system to categorize the intensity of the hurricane helps us to know the danger we are facing when the hurricane reaches land.
Hurricanes are one example of the force of nature. They can begin very small, but as they grow, they become more and more powerful. They only diminish as they begin to cross water that is cool or land. It is important to know if you live in an area in which hurricanes may hit, and also what to do in case of a hurricane. One of the most important things a person can do to save their own life is to evacuate if and when an evacuation order is given.