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Tornadoes
Tornadoes are whirl-winds which can occur any time in a year. Yet its occurrence proved to be greater during spring and early summer. That is tornadoes frequently occur during the month of April which will sometimes extend till May and June. April month is said to be the worst month meant for tornado destruction. The worst tornado hit happened on April 3 – 4, 1974 which slayed 300 people with 148 twisters striking 13 states.
Tornadoes are dark funnel-shaped clouds that violently rotate with a speed of up to 300 m.p.h. The diameter of a tornado generally vary from few feet And a mile and the track can extend from less than a mile to several hundred miles. Tornadoes travel in a north-east direction with a speed of up to 20 – 60 m.p.h.
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Causes of Tornado: Tornadoes are generally generated by giant thunderstorms known as “SUPERCELLS”. These powerful and highly harmful storms form when warm moist air rises forcibly upwards towards dry cold air. Sooner the warm air cools and the moisture in it condenses resulting in formation of a massive thundercloud sometimes growing much higher as 50,000 ft. Variable atmospheric winds at different levels feed the updraft forming the characteristic funnel shapes of the Tornadoes.
Tornadoes Occurrences: The formation of tornadoes are most often found in the Sothern and central U.S., since the warm, humid air from the Gulf of Mexico hits with cool, dry air from the Rockies and Canada. This area , dubbed “Tornado alley”, extends roughly from the Rocky Mountains to the Appalachians, and from Iowa and Nebraska to the Gulf of Mexico. Yet Tornadoes can occur elsewhere including all U.S. states, Europe, Asia and Australia.
Destruction by Tornadoes: The Tornadoes are generally classified according to the damages they cause by the Fujita Scale. Most tornadoes fall into F1 or “Moderate damage” category. These Tornadoes can reach speed of 73-112 m.p.h. and can overturn automobiles and mobile homes, uproot trees, rip off the roofs. Very few tornadoes are classified as F5 tornadoes that cause “Incredible damage”. These tornadoes can rise to speed of 261 m.p.h., lifting houses off their foundation and tossing them to considerable distances.
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