The storm ironically starts off as a mere wind whirling and slightly lowering pressures. After a while of receiving immense amounts of energy from warm moist air and nurtured by certain conditions of wind and pressure, the storms develop into high intensity full-fledged hurricanes heading toward the North and South Poles. New instruments and equipment are becoming more precise and scientists are exploring every dimension of the hurricane. The scientists test their vast reserves of energy and probing the complex mysteries of how hurricanes are created and how they become as strong as they do. Man can play with them to control their powerful forces or change their direction, but this could bring more bad than good. As hurricanes are very dangerous, they are also needed in some parts of the world to bring water.
What are hurricanes? A hurricane is a large, rotating storm with strong winds blowing at speeds of 74 miles an hour or more around a relatively calm center called the eye. Hurricanes blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. The storm can be 5 to 6 miles high and 300 to 600 miles wide. It moves forward acting as an immense spinning top at speeds of 12 miles and hour.
These storms are also called tropical cyclones in the northern part of the Indian Ocean in the Bay of Bengal and, typhoons in the western area of the North Pacific Ocean in Japan and Korea. They can dominate the atmosphere and the surface over thousands of square miles. They start in certain seasons in low latitudes in tropical oceans by the equator. The hurricanes move forward in a westerly direction parallel to the equator. Scientists now have the help of satellites, radar, and airplanes and keep close watch over the storms. The hurricanes are given names and are carefully tracked.
Scientists gaining ground on understanding the many factors that create hurricanes, they have yet to determine the exact processes of formation. A hurricane must have the exact ingredients of warmth and water vapor to supply its energy. It also must have a certain amount of convection activity and vertical wind motion to bring air from the sea level to move through the storm system. The hurricane also needs the exact amount of twist that the earth gives. A hurricane must obtain its energy from something. Huge amounts of energy are created when warm water is evaporated from tropical seas.
The hurricane stores this energy as latent heat in the water vapor which forms the clouds that circle the hurricane eye. 90 percent of this heat energy is released when the vapor expands. As the water vapor condenses into rain, 90 percent of the energy is released. As little as 3 percent is converted to mechanical energy, or energy of the circulating winds. The small amount of mechanical energy is equivalent to 360 billion kilowatt-hours per day. The total electrical energy the United States uses each day is only about 2 billion.
The mechanical energy of a hurricane in a single day is equal to about a six-month supply of electrical energy for the United States. The structure of the hurricane also defines it. The chaotic and violent hurricane has a definite structure and a well-defined pattern of winds. Scientists probe closer into these storms and find more about them.
A hurricane has an area of relative calm in the center that is called the eye. This is where the winds and clouds spiral in enormous bands. Around this eye, a bank of clouds blows, and this is the region of strongest winds. In the wall of clouds, the chimney or hot tower is located (Tufty, 18). This tower is the primary energy cell of a hurricane, where moist heated air moves upward from the ocean surface. As the winds spiral into the center of the storm, they bring in moist air in bands of precipitation called rainbands.
They can be 50,000 feet high and extend outward from the storm’s center for hundreds of miles. At the edge of the whole rotating storm, 200 to 300 miles from the eye, winds blow in short flurried gusts. The eye of the hurricane is the innermost portion of the storm, a zone of light breezes or no wind. In the eye, skies are often clear. Sunlight and starlight can stream all the way to the ground. Eyes are sometimes about 14 to 20 miles across.
In the Pacific Ocean, typhoons are often larger than other storms. The eyes are larger here and are sometimes are 50 miles in diameter. This is where the lowest pressures, the highest temperatures, and the lowest relative humidifies of the storm are found. Hot towers are the primary energy cells of a hurricane. They are located on or in the cloud wall that surrounds the storm’s eye.
The hot towers, also called chimneys, can be as high as 50,000 feet from the ocean. They are targets for weathermen trying to modify the storm’s energy by dropping chemicals into the storm from airplanes. Hurricane rainbands makes the heavy rainfall. They are in essence, bands of precipitation. They spiral in towards the storm’s center. They are long and narrow and vary in width from 3 miles to as much as 23 miles and the length of these bands may be more than 300 miles.
Some are 45,000 feet high, some are 20,000 feet, and some are even less high farther distances from the storm center. The outermost rainband may be several hundred miles away from the center. These rainbands predict the paths of winds bringing in warm moist air to feed the storm. The appearance of the spiral band structure changes as the storm moves and showers move in the band. Weathermen can track the movements of a storm from the rainband pattern. The number of rainbands can vary fom one to several.
There has been as many as 10. The direction of wind flow in a hurricane in the Northern Hemisphere blows spins inward counterclockwise. The size of hurricanes is different. Small hurricanes can be only 25 miles, and some bigger ones can be 400 to 500 miles. In the Pacific Ocean, they can be 1,000 miles. Some storms rise into the atmosphere 25,000 feet.
There are signs of approaching hurricanes. If one stands near the ocean shore, one signal of an approaching hurricane is a change in the sea. Along the coast where the storm is approaching, the level of the sea begins to rise. This can happen hours before the storm arrives.
Long waves begin to pound in the pattern that is different from ordinary waves. The storm approaches and the waves become heavier. Signals of a hurricane can also be seen in the sky. In the horizon, and spreading over the sky, cirrus appears, or high, feathery clouds which converge at one point on the horizon that may be the location of the storm center. As the sun sets or rises, the clouds on the outer border of the storm become highly colored red and orange. Falling pressure in a barometer also signals a hurricane.
The numbers of hurricanes that form annually is astounding. In the Northern Hemisphere, some experts calculated that in an active year for hurricanes, 50 such storms form in the Northern Hemisphere alone. Over a period of years, records of hurricanes average out with the following numbers: About 21 hurricanes a year formed in the southwestern part of the North Pacific Ocean. Many tropical cyclones form in the eastern North Pacific area. In the South Pacific Ocean, more than 20 severe storms form, many of which reach hurricane status (Tufty, 26). In the North Atlantic Ocean, about 10 hurricanes have been forming for the past 20 years.
The most recorded was 20 in 1933. The least was only 1 in 1890 and in 1914 & 2 in 1925 and 1930. The inter tropical convergence zone is an area where the prevailing trade winds of the Northern and Southern Hemisphere meet and converge. The zone follows the sun. The zone is highly irregular in diameter. Sometimes it can be strong and in a band 50 to 100 miles.
Other times it is hard to locate. Some hurricanes have lasted a few hours, and others have for several weeks. The life of a hurricane in the Atlantic is about 9 days. Storms in the month on August last the longest. They can go for 12 days.
Hurricanes are spotted and tracked. Hurricanes were made and stayed undetected for a long time. Today a huge network of instruments, men, and equipment at the National Hurricane Center in Miami, Florida look for potential hurricanes in their early stage and watch as they move. Hurricanes are observed from the air by satellites and research and commercial planes. At sea they are watched by buoys and ships.