How Are The Hurricanes Formed?
Posted under Hurricane, SCIENCE & TECHNOLOGY on Dec 17, 2008
Hurricanes are the strongest of the windy and circulating storms, and are often called cyclones. They are prominent in the Atlantic and eastern Pacific oceans and in the western Pacific they are referred to as typhoons.
Most Atlantic hurricanes are born in the southern Atlantic Ocean, off the coast of Africa, in the months of June through November each year.
How Hurricanes form?
During this time, winds off the west coast of Africa converge, circulating counterclockwise. These winds often maintain a low speed and travel across the Atlantic Ocean as tropical waves, causing little more than rainfall on the land masses on which they strike.
Other times, when the water temperatures are warm enough and atmospheric conditions are correct, the wind speeds increase and begin to form around a center, or the eye.
Hot and moist air from the ocean is then pulled up into the eye of the storm, which is now called a tropical storm.
As the air rises it cools and moisture condenses and is released as heavy rain into the torrential winds that circulate around the eye.
The released energy is pumped into the rotating cloud mass, which makes it rise and spin even faster. The storm has become a hurricane by the time the winds reach speeds of 119 kmph, equal to 74 miles per hour.
As the spinning storm moves across the ocean wind speeds increase. Hurricanes are typically classified by the strength of their winds into five categories on the Saffir-Simpson Hurricane Intensity Scale.
The weakest hurricanes have wind speeds that are between 74-95 miles per hour and are referred to as Category 1 storms.
Category 1 storms cause minimal damage primarily to plants and trees. In 1992, Hurricane Andrew was Category IV storm with sustained wind speeds of 140 miles per hour.
Category V storms, such as Hurricane Camille, are the strongest storms and are responsible for catastrophic damage.
Hurricane Camille, with sustained winds of more than 200 miles per hour, was the most powerful hurricane ever recorded in the northern gulf coast.
Difference in wind speed is one easy way to classify storms, but hurricanes also have other unusual characteristics.
Some storms move quickly and produce little rainfall, while others are slow and generate torrential rainfall with downfalls that often exceed 15 inches.
One characteristic that all storms have is the location of the most powerful and dangerous winds. The forward right quadrant of a hurricane is its strongest and most dangerous section.
This is the most dangerous section because the counterclockwise motion of the storm, as well as its forward movement, fuels it.
As the storm moves along the ocean surface, it becomes a complex and tight mass of wind and rain. The eye becomes perfectly clear on satellite pictures and larger hurricanes can have an eye as large as 35 miles in length.
The hurricane’s eye is the area around which the winds rotate and is actually a calm area in the center of the storm.
Many people have been deceived into thinking the storm had ended when the eye passed over and were surprised when the destructive winds began again.
Hurricanes can contain and release enough energy to supply electricity to the United States for a year. Hurricanes also carry the ocean with them, which can bring storm surges as high as 25 feet above sea level.
Often the accompanying storm surge and associated floods are responsible for much of the damage caused in coastal areas. Storms pursue unpredictable paths toward land.
There is no set pattern in the journey from where they originated in Africa. They frequently move northwesterly to the Gulf of Mexico and eastern coasts of North and Central America.
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