1. Natural Disasters Tornadoes, Flooding, and Avalanches

3. 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

5. Tornadoes – What Causes Them? Develop in warm, moist air as they are met with cold fronts Creates atmospheric instability, which causes a spinning updraft

7. Supercell Thunderstorms Long line of thunderstorms whose updrafts/downdrafts are in perfect balance Deadly: Perfect conditions for many tornadoes

8. Wall Cloud Rain-free clouds that accompany tornado- producing thunderstorms

10. Waterspouts Tornadoes that form over water

11. 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

12. Floods Most often, caused by overflow of rivers/lakes for a variety of reasons Farmhouses, vehicles and farmland ruined Can contaminate water

15. Why Live Near Water? Humans value the proximity to water Land cost is cheaper near water; easier access to transportation

16. Flood Control Levees/Reservoirs In emergencies, sandbags

20. 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

21. Deadliest Flood China Flood, 1931 Est. deaths: 400,000-4,000,000 Left 80,000,000 homeless

22. Three Gorges Dam Built to help control flooding and control China’s 3 main rivers