Atmosphere And Weather

Super Storms



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What are super storms? Storms are atmospheric disturbance manifested in strong winds accompanied by rain, snow, or other precipitation and often by thunder and lightning.

There is no strict definition for what a super storm is. Very powerful storms that have strong hurricane-type force winds and cause snowstorms, blizzards, storm surge, beach erosion, and flooding are categorized as super storms. They typically occur during the winter.

The Saffir-Simpson scale rates hurricanes on a scale of 1 to 5 according to wind speeds and destructive potential. Super Storms reach Category 5, where winds blow continuously above 250 kilometers an hour (155 miles per hour). The largest ever super storm, the 1979 Pacific typhoon Tip, sent gale-force winds across more than 650 miles (1,000 kilometers).

How storm systems develop

When air is heated, they become less dense and tend to rise. When the temperatures at the surface of the oceans reach 27 degree centigrade, there is very little wind shear or difference in wind speeds at the surface and aloft, and waves are absent, the warm, moist air over the ocean tend to rise rapidly upward from near the surface. This result in lesser air near the surface and creates a sudden low pressure. Air in surrounding areas with higher air pressure follows the law of nature and rush in to this newly formed low-pressure area. Since the heat is intense, this "new" air too quickly becomes warm and moist and they too rise rapidly, repeating the process. The surrounding air swirls to take the place of the rising air, intensifying the process.

By this process, the moist air propel themselves to an altitude of 50,000 feet (15,000 meters) or more, where they finally condense into spiraling exhaust jets of cirrus clouds. Meanwhile, if the rapid rise of moist air continues, these clouds intensify and eventually precipitate. This swirl and precipitation, fuelled by the heat of the sun, and the water of the ocean lead to storms. The swirl forms tornadoes.

When the winds in the rotating storm reach 39 miles per hour, the storm is called a "tropical storm" and when the wind speeds reach 74miles per hour, the storm is officially a "tropical cyclone", or hurricane. In the western Pacific, hurricanes are called typhoons.

How storms become super systems

When ocean temperatures are high, several such storms systems would form simultaneously in different parts of the ocean.

Jet streams are fast flowing and relatively narrow air currents found in the Earth's atmosphere at around 11000 meters above sea level. These jet streams direct two or more of such storms system to join. When this happens, the instability accentuates, and the storm grows in size and wind velocity to become a super storm.

Jet streams also play their part in intensifying the storm system and elevating them to super storms. The tropical ocean is littered with deep warm pockets and the jet stream would take the swirling storms through these hot pockets. Both Katrina and Rita shot up to Category 5 when they passed over a deep band of warm Gulf water called the Loop Current.

In a typical setup for a super storm that lashes the Mid Western United States, one storm start to develop and move with the jet stream to reach the east coast. Meanwhile, a tropical storm from the Atlantic Ocean merge with another tropical storm becomes a hurricane and begins to move north. The jet stream then brings these two or three storm systems together, and it begins to strengthen and develop into a super storm.

Professor James McCarthy at Harvard University predicts that global warming is likely to intensify the formation of super storms. With global warming, large parts of the world's oceans are approaching 27 degrees centigrade or warmer during the summer, greatly increasing the odds of major storms. As emissions of greenhouse gases continue to trap more and more of the sun's energy, the need to dissipate such energy could result in stronger storms, more intense precipitation and higher winds, all favoring super storms.

Impact of super storms

Tropical cyclones usually weaken when they hit land, because they are no longer being "fed" by the energy from the warm ocean waters. However, by the time they dissipate they often move far inland, dumping many inches of rain and causing lots of wind damage. Super storms, charged several times more than ordinary storms wreck devastation deep into the interiors before they dissipate.

A majority of the super storms affects Eastern United States, including cities such as New York, Boston, Philadelphia, Washington D.C.. These three super storms of 2005, Katrina, Rita and Wilma were part of an unmatched run of Atlantic hurricanes-15 in all. Meteorologists had until that point named 21 Atlantic cyclones based on their characteristics and now had to dip into the Greek alphabet for the latecomers. Katrina is the costliest natural disaster in US history and left New Orleans and the neighboring coast in ruins. Rita that followed rivaled Wilma in intensity and ravaged the Gulf Coast through western Louisiana and East Texas.

REFERENCES:

http://spaceplace.nasa.gov/en/kids/goes/hurricanes/
http://ipsnews.net/interna.asp?idnews=25542
http://library.thinkquest.org/C0111179/hurridiff.html

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