Transcript hurricane
General Science 1 Spring ‘08 Hurricane Season Occurs between June 1-November 30 Threatens the Gulf Coast of the US, Eastern Coast, Mexico, Central America and Caribbean “hurricane” in the Atlantic ocean “typhoon” in Asia “cyclone” in Australia Hurricane Terms A tropical cyclone (low pressure area) that occurs in the North Atlantic. Tropical depression Rita Tropical storm Boris Tropical depression- winds less than 39 mph Tropical storm- Winds between 39-74 mph and given a name Hurricane- winds 75mph or greater Characteristics of Hurricanes Tropical- form in tropical areas near equator with water temps. near 80oF. Cyclonic- winds swirl around a central eye Counter clock wise in northern hemisphere Clock wise in southern hemisphere Low-pressure systems- eye is always a very low pressure Parts of a hurricane Eye- low pressure center, calm area Eye wall- area around the eye, fastest, most violent winds Rain bands- bands of thunderstorms circulating outward from the eye; feeds the storm How a Hurricane Forms Begin off west coast of Africa as thunderstorms They move east over warm, tropical waters It can take several hours or days for a hurricane to form Warm, moist air over the ocean rises quickly, condenses and forms clouds Rising air is replaced by warm, humid air from below. Cycle continues, drawing warm air inward. Air moves from areas of high to low pressure, so more air is pulled inward, feeding the hurricane Circulation and wind speeds increase Size and Location Hurricanes vary widely in size Can spread out over hundred to thousands of miles Hurricane Danny (left) in 1997 and Hurricane Fran in 1996 show the variability in hurricane size Watches and Warnings Tropical Storm Watch- 39-75 mph winds possible within 36 hours Tropical Storm Warning- conditions likely within 24 hrs Hurricane watch- hurricane conditions possible within 36 hours Hurricane warning- hurricane within 24 hrs Damage Caused by: Rain (up t0 40 inches!) Flooding (due to the rain) Winds (75 mph or greater) Storm surge wall of water that comes in front of a hurricane Created by wind Increases flooding/erosion tornadoes Damage Depends on 3 Things Strength of storm 2. If it hits land 3. Right or left side of eye strikes an area- right is worse (winds/rain stronger) 1. Saffir-Simpson Scale Category 1 74-95 mph winds Some flooding Hurricane Isabella as a Cat. 1 on 9/19/05 Little to no damage Category 2 96-110 mph winds Trees down Roof damage flooding Saffir-Simpson Scale Category 3 111-130 mph winds Structural damage to homes Mobile homes destroyed Severe flooding Loss of life Category 4 131-154 mph winds Sever flooding inland Major structural damage (roofs ripped off ) Loss of life Saffir-Simpson Scale Category 5 Greater than 155 mph winds! Severe flooding further inland Severe damage to most wooden structures Loss of life Hurricane Katrina as a Category 5 on August 28, 2005. One day before making landfall on the Gulf Coast www.hurricanekatrina.com Hurricane Andrew (1992) Money to Rebuild FEMA- Federal Emergency Management Agency Created in 1979 Headquarters in Washington, DC A small agency with only 2,600 full-time workers, and nearly 4,000 other workers called Disaster Assistance Employees. These workers are on stand-by to respond after a disaster happens. Became part of the Department of Homeland Security on March 1, 2003. In charge of helping people before and after a disaster. Called in to help when the President declares a disaster. Disasters are “declared” after hurricanes, tornadoes, floods, earthquakes or other similar events strike a community. Hurricane Katrina One of the five deadliest hurricanes in US history. 6th strongest Atlantic hurricane ever recorded. 3rd strongest hurricane on record to make landfall. Formed on August 23, 2005. Hurricane Katrina Most severe damage in New Orleans, LA. At least 1,836 people lost their lives. Estimated $81.2 billion in damage (2005) making it the costliest natural disaster in US history. Katrina Montage Political Aftermath Poor response by FEMA But the National Hurricane Center and the National Weather Service were widely commended for accurate forecasts and abundant lead time.