1. Lesson 7: Natural Hazards Tornadoes

2. A tornado is a violent rotating, funnel of air that extends from a thunderstorm to the ground.

3. Winds in most tornadoes blow at 100 mph or less.
In the most violent and least frequent tornadoes, wind speeds can exceed 250 mph.

4. Tornadoes are caused by long-lasting, large thunderstorms.

5. Before thunderstorms develop there is: a change in wind direction and
Stronger west
Winds aloft
Southeast wind
Near ground
Before thunderstorms develop there is:
a change in wind direction and
an increase in wind speed with increasing height
This creates an invisible, horizontal spinning effect in the lower atmosphere. 5

6. Rising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical. 6

7. An area of rotation, 2-6 miles wide, now extends through much of the storm.
Most strong and violent tornadoes form within this area of strong rotation. 7

8. Tornadoes: Shapes and Sizes
Weak Tornadoes
69% of all tornadoes
Less than 5% of tornado deaths
Lifetime minutes
Winds less than 110 mph 8

9. Tornadoes: Shapes and Sizes
Strong Tornadoes
29% of all tornadoes
Nearly 30% of all tornado deaths
May last 20 minutes or longer
Winds mph 9

10. Tornadoes: Shapes and Sizes
Violent Tornadoes
Only 2% of all tornadoes
70% of all tornado deaths
Lifetime can exceed 1 hour
Winds greater than 205 mph 10

11. Tornado Risk Areas. 11 August 2012. http://training. fema

12. Regions of the World Most Prone to Tornadoes. 31 August 2012

13. Effects of Tornadoes 13

14. Effects of Tornadoes 14

15. http://upload. wikimedia 15

16. Who is most at risk? People in automobiles
The elderly, very young, and the physically or mentally impaired
People in mobile homes
People who may not understand the warning due to a language barrier 16

17. Warning Systems
Tornado Warning Systems are often run by county governments and use data from the National Weather Service. 17

18. Warning Systems
TORNADO WATCH: Tornadoes are possible in your area. Remain alert for approaching storms. 18

19. Warning Systems
TORNADO WATCH: Tornadoes are possible in your area. Remain alert for approaching storms.
TORNADO WARNING: A tornado has been sighted or indicated by weather radar. If a tornado warning is issued for your area and the sky becomes threatening, move to your pre-designated place of safety. 19

20. MYTH: Areas near rivers, lakes, and mountains are safe from tornadoes.
Tornado Myths
MYTH: Areas near rivers, lakes, and mountains are safe from tornadoes. 20

21. What is a myth? Two Definitions
A traditional, typically ancient story dealing with supernatural beings or phenomena or explaining aspects of the natural world or outlining the customs or ideals of society.
A fiction or half-truth

22. Tornado Myths
MYTH: Areas near rivers, lakes, and mountains are safe from tornadoes.
FACT: No terrain is safe from tornadoes. In the late 1980's, a tornado swept through Yellowstone National Park leaving a path of destruction up and down a 10,000 ft. mountain. 22

23. Tornado Myths
MYTH: The low pressure with a tornado causes buildings to "explode" as the tornado passes overhead. 23

24. Tornado Myths
MYTH: The low pressure with a tornado causes buildings to "explode" as the tornado passes overhead.
FACT: Violent winds and debris slamming into buildings cause most structural damage. 24

25. Tornado Myths
MYTH: Windows should be opened before a tornado approaches to equalize pressure and minimize damage. 25

26. Tornado Myths
MYTH: Windows should be opened before a tornado approaches to equalize pressure and minimize damage.
FACT: Opening windows allows damaging winds to enter the structure. Leave the windows alone; instead, immediately go to a basement, interior room, or bathroom without windows. 26

27. Michigan Citizenship Collaborative Curriculum
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