A view from the air--Where have the forests gone? (Sierpe River Area, SW Costa Rica)
Hurricanes are dangerous, life-threatening storms. They are the biggest storms on Earth and one of the most destructive forces known to mankind. I would like to inform you on what a hurricane is and how it is formed. I would also like to explain each part of a hurricane and also how hurricanes are classified. I think this information will be vital to us because we are study land that has been affected by hurricanes.
First of all, I would like to clearly explain exactly what a hurricane is. A hurricane is a large storm that forms in the tropics over the oceans. Different parts of the world have different names for these storms. They are called cyclones in the Indian Ocean and near Australia, and typhoons in the western Pacific. In the rest of the Pacific Ocean, the Atlantic Ocean, the Caribbean, and the Gulf of Mexico they are called hurricanes. Similar storms in Australia are called willy-willies (Lee 11).
The name hurricane came from the Mayas of Central America. They considered the great storm to be Huracan, a god of big winds and evil spirits. Once a year the Mayan nations would sacrifice a young woman to the god Huracan to pacify him. She was hurled into the sea. A warrior was also sacrificed with her to guide her into the watery kingdom of Huracan. Spanish explorers in the area learned his name from the native people. That is how it became todayÍs word for hurricane (Archer 13).
Hurricanes are storms that have winds that blow faster than 74 miles per hour. Speeds of 100-150 miles per hour are more common. In rare instances, wind speed may reach 200 miles per hour. They are born over the warm tropical oceans near the equator. They start as small as a thunderstorm and can grow in size and strength until they measure 200-250 miles across. The whole storm moves forward and can last days or even as long as weeks.
There are various factors that cause hurricanes to develop. The first facto is the temperature of the ocean water. The most common place for a hurricane to form is in two general bands. These bands are between 5 degrees and 30 degrees latitude north and south of the equator. This is because the ocean waters here are warmer. The air above the heated ocean grows lighter and rises. This air (wind) is a major factor in the development of hurricanes. The heat from the ocean causes the air to rise faster and faster. Just like hot air rising in a chimney. Cooler air from above moves down to take the place of the rising warm air. The two types of air (warm and cool) converge together and the cool air spins counter clockwise around the warmer air. As the warm air rises, the pressure drops making the winds blow stronger. It takes about a half a day for the air to begin circulating counterclockwise. Storms clouds are formed with winds that gradually grow stronger and stronger. They whirl faster and faster. When the speeds of these winds reach 75 miles per hour, they become a hurricane.
The cycle of how a hurricane forms is started by the continuous growth of storm clouds. When there is a large area of thunderstorms that last more than a day, it is called a tropical disturbance. These are quite common in the tropics. Air from an area surrounding the tropical disturbance begins to flow inward toward the center by the Coriolis force. The Coriolis force is a result from the rotation of the Earth. It causes winds in low-pressure systems to curve counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. When the winds begin to circle around a poorly defined center, the storm is called a tropical depression. It contains thunderstorms and wind speeds less than 38 miles per hour. A depression becomes a tropical storm when its winds reach 39 miles per hour. When the pressure of the tropical storms continues to drop and its winds increase to more than 74 miles per hour, it is officially a hurricane (Lampton 28).
Hurricanes develop in the times of the year when the seas are at their warmest and the air above them become heavy with moisture. This is when hurricane season begins in the tropics. Over the western Pacific, storms usually form from June through October. Along the Atlantic and Gulf coasts, they generally appear from June through November. There are instances when hurricanes developed outside these designated months. For instance, in 1955 Tropical Storm Alice grew into a hurricane on January 4. Frequently June and July storms that affect the United States begin in the Gulf of Mexico and the Caribbean Sea. In August, as parts of the Atlantic warm up, storms develop further out at sea. Early September is the height of hurricane season. In October the storms return to the Caribbean and the Gulf of Mexico. Many of the hurricanes that head toward the United States originate as far away as the Cape Verde Islands, off the coast of West Africa. Hurricane Andrew started in this region in 1992 (Souza 26).
The parts of the hurricane resemble a bullÍs eye. In the center you have the eye. The eye is an area of calmness surrounded by the violently whirling winds. Here winds are lighter and the skies are clear or partly cloudy. It is the warmest part of the hurricane and it has the lowest air pressure. The eye averages 15 miles across. The eye can be deceptive. People may think the hurricane is over and venture out into this calmer area may be hit suddenly by the violent winds on the back side of the storm. Surrounding the eye is the eye wall, a more or less solid bank of thunderstorms 5 to 30 miles wide. The eye wall contains the most damaging winds and produces the heaviest rain of the storm. Rainbands give hurricanes their pinwheel appearance on satellite photos. These are a series of dense clouds that spiral in toward the center of the storm. The outer edges of the rainbands may reach the shore several hundred miles ahead of the eye itself. The canopy of clouds caused by the warm moist air rising rapidly through the storm is called the outflow shield. The air spirals out of the top and is carried away by high altitude winds creating the canopy of clouds. The most dangerous part of the hurricane are the storm surges. Like a giant straw, the low pressure in the center of the hurricane sucks up a mound of water about a foot high and 50 miles wide. As the center of the hurricane moves over land, this mound of high water is carried a short distance inland. The surge can raise the level of the sea by as much as 20 feet. This sudden rise in sea level pushes water further onto shore and can cause serious flooding to oceanfront property. The storm surge is not a giant wave it is just a sudden rise in sea level. It is also dangerous when it rushes upon a flat coastal area. The surge is topped by large breaking waves that have been whipped up by the wind. These powerful waves can smash structures not designed to withstand their force. They can sweep away people, animals, and anything else in their way (Lee 29).
Hurricanes are classified by the Saffir-Simpson Scale. It considers such things as barometric pressure, wind speed, and storm surge. The scale ranks hurricanes from 1 to 5. Category 1 is the least dangerous and Categories 4 and 5 are the most serious. A storm is named when it becomes a tropical storm. This gives meteorologists an easy way to refer to the storm when tracking it. In 1953 the U.S. Weather Bureau officially starting naming hurricanes after women. In the 1970Ís menÍs names, as well as Hawaiian and Spanish names, were added. Now alphabetical lists alternating male and female names are used. The lists of names for North Atlantic hurricanes are repeated every six years. If a hurricane has been especially deadly or damaging, its name is removed from the list (Lee 23).
It is not possible for us to stop hurricanes, but it is possible for us to predict them. The first spotters of hurricanes are the weather satellites. Most of these satellites were placed in orbit by the National Oceanographic and Atmospheric Administration (NOAA). The satellites orbit many thousands of miles above the earthÍs surface and send pictures to meteorologists. These satellites monitor the movement of a tropical storm as they approach populated coastlines. Weather balloons also help in predicting hurricanes. These balloons are equipped with measuring instruments and they are launched twice a day around the world. They help scientists spot changes in temperature and water vapor in the atmosphere. Computers help meteorologists study hurricanes in two ways. First, computers receive enormous amounts of weather data collected from satellites, radar, airplanes, weather balloons, ground stations, and other sources. Computers can also recreate pictures of hurricanes. Instead of studying an actual storm, scientists can study computer models to learn how hurricanes develop and behave (Lauber 29).
Now that we know what a hurricane is, where it originates, and how they are detected, I would like you to know what to do if a hurricane is approaching us. If a hurricane watch is issued in the area, we have more than 24 hours to know if the storm is headed our way. This is when you listen to the radio or watch the television for updated bulletins about the storm. If a hurricane warning is issued, listen carefully for directions. We may have to evacuate the area as soon as possible. If there is no evacuation needed, there are other things we can do to ensure our safety as best as we can. We should remove anything outside that might blow away due to the high winds, we should fill water containers in case water mains break, and we should have plenty of food and supplies close by. Once the storm arrives, we should stay indoors and away from wall and windows that might collapse or blow away. If it is nighttime, we should have a flashlight close by incase of power failure. Once it is alright to go outside after the storm has blown over, stay away from downed power poles, live wires, dangling tree branches, and broken water or sewer mains (Souza 42).
As you can see, hurricanes are dangerous, life threatening storms. They are very complex and difficult to predict exactly what a hurricane is going to do. The best thing to do in case a hurricane is in the area is to listen to what the meteorologists tell you. They have the technology to predict the hurricanesÍ actions. I hope this information about this dangerous storm helps you the next time you come in contact with this monstrous storm.
Archer, Jules. Hurricane!. Crestwood House. New York, 1991
Lampton, Christopher. Hurricane. Millbrook Press. Brookfield, CT, 1991
Lauber, Patricia. Hurricanes. Scholastic Press. New York, 1996
Lee, Sally. Hurricanes. Franklin Watts. New York, 1993
Souza, D.M. Hurricanes. Carolrhoda Books Inc. Minneapois, 1996
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