1. Hurricanes and Tornadoes
See video “Twister”

2. What Do Hurricanes and Tornadoes have in Common?
Low Pressure
Latent Heat of Condensation
Strong Winds
Hazardous to Life and Property

3. How Do They Differ? Location Size Duration Season of Occurrence
Distinctive Hazards

4. When Do They Occur? Hurricane season? Late Summer and Fall
Tornado season?
Spring and Early Summer

5. Location – Where Do Storms Form?
Hurricanes form over warm (27* C) tropical seas or higher
Latitude 7-15 degrees N and S of the equator
Tornadoes form over land in mid latitudes

6. See “Hurricanes 101 video”

7. Tracks of Hurricanes Hurricanes die out over land Why?
Friction and loss of moist air from ocean

8. Size and Duration of Hurricanes
Hurricanes typically 600 km wide
Last days
Rate of travel approximately 10 km/h
Travel with Trade Winds

9. Hurricane Structure Intense low pressure system Over 120 km/h winds
Strong convectional lifting
Eye with calm, clear conditions

10. Hurricane Structure Air cools off quickly the higher you go
Wind must be blowing in the same direction and at the same speed to force air upwards from ocean’s surface
Winds flow outward above the storm, allowing the air below to rise
The Coriolis force is needed to to create the spin in the hurric

11. Hurricane Damage High winds 120-200 km/h Torrential rains Flash floods
Storm surges as sea level rises
See video “Hurricane Katrina day by day”

12. Storm Surge
-Storm surge is a rise of water levels as a result of the hurricane (they bring a lot of precipitation with them)

13. Storm Surge

14. Hurricane Video
See videos “Hurricane Sandy: A once in a generation storm” &
“Hurricane Sandy: Cruise ship”

15. Tornado Video
See Video “Tornadoes 101”

16. Formation of Tornadoes
Warm moist air flows into a storm and gets twisted by upper level winds
This rotating column of air gathers force and produces a tornado

17. Location of Tornadoes Most common in the United States
Plains States, Midwest, and Florida
In advance of a cold front
Embedded in hurricanes
Narrow intense storm
1/2 km wide
path of 6 miles SW to NW
A few minutes to three hours

18. Structure of a Tornado
Cumulonimbus cloud
A narrow funnel
A dust cloud

19. Size and Duration of Tornadoes
Narrow intense storm
1/2 km wide
path of 10 km SW to NW
A few minutes to three hours

20. Tornado Hazards Wind Speed 150-450 km/h Strong updraft in the funnel
Explosions due to pressure contrast

21. Review Which is larger, a hurricane or a tornado?
Which moves faster, a hurricane or a tornado?
Which lasts longer?
Where do hurricanes form?
Where do tornadoes form?