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Video A - Hurricane Katrina.docx

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Western University
Geography 2152F/G

GEOG 2152F: Geography of Hazards Video: Hurricane Katrina (The Storm that Drowned a City) 1. What is a tropical depression? Describe the origins of Hurricane Katrina. - starts off as a small storm called a tropical depression - Tropical depression: a center of low atmospheric pressure - In the warm waters of the eastern Atlantic, water vapor rises from the ocean then cools, forming clouds and releasing heat energy which fuels the storm - This sucks in more warm air, generating strong winds, which shoot upwards - When this rush of air hits the stratosphere, it flattens out, and, influenced by the Earth's rotation, the storm starts turning counterclockwise. - As soon as the winds reach 39 miles per hour, the depression is considered a tropical storm (a day later after Katrina starts off as a tropical depression, the Hurricane Center upgraded it to a tropical storm) - Roughly half of all tropical storms become hurricanes 2. How have we been improving the forecasting of hurricanes? - Hurricane forecasts are improving due to a greater understanding of atmospheric dynamics and more extensive satellite coverage. - Relying very heavily on remote sensing via satellites - But if more data needed, sent out the Air Force hurricane hunters  fly right into the approaching storm, so external sensors record wind speed, pressure and temperature to build up a more detailed picture of Katrina o new piece of technology has been added: dropsonde o released through a chut in the floor, as it floasts down to the surface it radios back data o acts like a weather balloon: collecting temperature, relative humidity, and pressure; also a GPS module that will be affected as it shifts from one point to the next (giving wind direction and wind speed at different points in the storm) - also have faster supercomputers at Hurricane Center, also using improved computer modeling so longer-day forecasts are getting more accurate - however, intensity is still difficult to predict because the inner storm can change minute by minute 3. What was the engineering approach to protect the city? What were its limitations? - To protect the growing population, the state built earthen levees back in 1900s - But these banks can burst - The Army Corps of Engineers and the federal government build and repair levees (especially the Mississippi River levees in the city of New Orleans and southern Louisiana) - New Orleans has two types of levee: the original earthen levees and more recently built concrete and steel floodwalls - However, these levees can only withstand up to Category 3 hurricanes. 4. What role do wetlands play? How have they been altered and what has been the impact? - The wetlands used to provide defense against Hurricanes - The Mississippi River conveyed tons of silt and soil to the coast each year. Every spring, when the river flooded, the wetlands were stre
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