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Natural Disasters. Tornadoes, Flooding, and Avalanches. Tornado Facts. Mainly occur east of Rocky Mountains in US Spring/summer 800 tornadoes reported nationwide Speeds up to 250 MPH; damage paths 1-50 miles long. Tornadoes – What Causes Them?.
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Natural Disasters Tornadoes, Flooding, and Avalanches
Tornado Facts • Mainly occur east of Rocky Mountains in US • Spring/summer • 800 tornadoes reported nationwide • Speeds up to 250 MPH; damage paths 1-50 miles long
Tornadoes – What Causes Them? • Develop in warm, moist air as they are met with cold fronts • Creates atmospheric instability, which causes a spinning updraft
Supercell Thunderstorms • Long line of thunderstorms whose updrafts/downdrafts are in perfect balance • Deadly: Perfect conditions for many tornadoes
Wall Cloud • Rain-free clouds that accompany tornado-producing thunderstorms
Waterspouts • Tornadoes that form over water
The “F” Scale • F0: Winds less than 73 MPH • F1: 73-112 MPH • F2: 113-157 MPH • F3: 158-206 MPH • F4: 207-260 MPH • F5: 261-318 MPH
Floods • Most often, caused by overflow of rivers/lakes for a variety of reasons • Farmhouses, vehicles and farmland ruined • Can contaminate water
Why Live Near Water? • Humans value the proximity to water • Land cost is cheaper near water; easier access to transportation
Flood Control • Levees/Reservoirs • In emergencies, sandbags
Benefits of Flooding • Egypt benefits from silt/clay deposits; soil becomes very fertile • Indus/Ganges in Bangladesh • Humans thrive off of rich soil for crops
Deadliest Flood • China Flood, 1931 • Est. deaths: 400,000-4,000,000 • Left 80,000,000 homeless
Three Gorges Dam • Built to help control flooding and control China’s 3 main rivers