Presentation on theme: "What is a hurricane? A severe, rotating tropical storm with heavy rains and cyclonic winds exceeding 74 mph."— Presentation transcript:
What is a hurricane? A severe, rotating tropical storm with heavy rains and cyclonic winds exceeding 74 mph.
1.Tropical wave A low pressure trough of persisting winds that blow from east to west. 1.Tropical disturbance An organized area of thunderstorms generally miles in diameter. Typically, a tropical disturbance maintains its identity for at least 24 hours and is accompanied by heavy rains and gusty winds. 1.Tropical depression An organized area of tropical low pressure in which sustained winds are 38 miles per hour or less.
1.Tropical storm A tropical cyclone with maximum sustained wind speeds of miles per hour. and accompanied by thunderstorms. 1.Hurricane A tropical cyclone with maximum sustained winds of at least 74 miles per hour and accompanied by thunderstorms. In the Northern Hemisphere, hurricane winds circulate in a clockwise rotation.
The development of a hurricane. 1. Several thunderstorms start rotating around a low pressure system. (Tropical depression) 2. When winds reach MPH it becomes a tropical storm. 3. When winds reach over 74 MPH the storm becomes a hurricane.
The life of a hurricane Hurricanes will strengthen (grow) as long as they have a warm water supply. Hurricanes die when they move away from warm water or onto land. Clouds rising into the atmosphere and being turned by the rotation of the earth (Coriolis effect) causes the hurricane to spin. Hurricanes do not form within 300 miles of the equator because there is no Coriolis effect.
Parts of a hurricane The spiral rain bands are areas of gusty winds and heavy rains that are fed by the warm ocean water. Eye wall has heavy rain and winds as well. The air is moving rapidly towards the center. Eye = forms when the rising warm, moist air sinks.
Storm surge Produced by the wind that surrounds a hurricane. The wind pushes the water ashore.
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Naming Hurricanes Early Atlantic hurricanes were named after the saint of the day from the Roman Catholic liturgical calendar. If two hurricanes struck on the same day, separate years, it was referenced as “the first” or “the second.” During WWI meteorologists began using female names to refer to hurricanes. In 1979, male names were introduced for hurricanes.
Hurricane names continued. There are currently six lists that are used and rotated through. Some names are retired as a way to honor those lives lost in severe hurricanes. When there are more than 21 names (Q, U, X, Y, & Z are not used) the Greek alphabet is used.
Hurricane name list 2014
The Saffir-Simpson Hurricane Scale A 1-5 rating based on the hurricane's present intensity. This is used to give an estimate of the potential property damage and flooding expected along the coast from a hurricane landfall. Wind speed is the determining factor in the scale.
Category 1 No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Some damage to poorly constructed signs. Also, some coastal road flooding and minor pier damage. Hurricanes Allison of 1995 and Danny of 1997 were Category One hurricanes at peak intensity.
Category 2 Some roofing material, door, and window damage of buildings. Considerable damage to shrubbery and trees with some trees blown down. Considerable damage to mobile homes, poorly constructed signs, and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of the hurricane center. Hurricane Bertha of 1996 was a Category Two hurricane when it hit the North Carolina coast
Category 3 Some structural damage to small residences and utility buildings. Damage to shrubbery and trees with foliage blown off trees and large trees blown down. Mobile homes and poorly constructed signs are destroyed. Flooding near the coast destroys smaller structures with larger structures damaged by battering of floating debris. Terrain continuously lower than 5 ft. above mean sea level may be flooded inland 8 miles (13 km) or more. Hurricanes Roxanne of 1995 and Fran of 1996 were Category Three hurricanes.
Hurricane Sandy 285 deaths. Highest wind = 115 MPH Diameter was 1,100 miles
Hurricane Sandy Oct. 29, 2012
Four days after the storm.
Category 4 Shrubs, trees, and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors and windows. Major damage to lower floors of structures near the shore. Terrain lower than 10 ft. above sea level may be flooded requiring massive evacuation of residential areas as far inland as 6 miles (10 km). Hurricane Luis of 1995 was a Category Four hurricane while moving over the Leeward Islands. Hurricanes Felix and Opal of 1995 also reached Category Four status at peak intensity.
Category 5 Complete roof failure on many residences and industrial buildings. All shrubs, trees, and signs blown down. Complete destruction of mobile homes. Severe and extensive window and door damage. Major damage to lower floors of all structures located less than 15 ft. above sea level and within 500 yards of the shoreline..
Katrina 2005 Made landfall on Florida on August. 25 th as a category one. Regained strength in Gulf to become a category 5. Made landfall again on August 29 th as a category 3. The levees that protected New Orleans broke and it flooded.
80% of New Orleans flooded. Top winds were 174 MPH. 1,833 confirmed deaths. Spawned 33 tornadoes.