1. Thunderstorms

2. What causes Thunderstorms
Occur inside warm, moist air masses and at fronts.
Warm/humid air rises rapidly, cools, condenses and forms CUMULONIMBUS clouds.

3. Two Types of T-Storms Air Mass T-Storms: (Sporadic)
Caused by convection currents of air.
Mountain T-Storm – Orographic Lifting
Sea-Breeze T-Storm – Afternoon T-Storm at the beach.
Most Common T-Storm
Frontal T-Storm: (Wall of Storms)
Caused by Frontal Lifting: Cold and Occluded Fronts

4. Stages of a Thunderstorm

5. Stages of Thunderstorm Development con’t
Causes:
Think: L.I.M.
Lift
Instability
Moisture
Video

6. Lightning Rapid Uplift of air builds electrical charges.
Some parts of the cloud contain negative charges and some contain positive
When current flows from (-) to (+) lightning flashes
Video: Anatomy of a Lightning Strike

7. Lightning Pathways Lightning can travel from: Cloud to Cloud
Cloud to Ground
Ground to Cloud

8. Lightning & Thunder
Results from the rapid heating of air around lightning.
Heat causes rapid expansion of the air
Molecules move faster than the speed of sound creating a “sonic boom”
Video

9. Determining the Distance of a Thunderstorm
For every five seconds between the lightning and thunder, the cell is one mile away.

10. Tornadoes

11. How a tornado starts:
Winds are stronger aloft than at the surface (called speed wind shear), producing a rolling motion about a horizontal axis.
Strong thunderstorm updrafts tilt the horizontally rotating air to a nearly vertical alignment.
The mesocyclone, a vertical cylinder of rotating air, is established.

12. Tornado Formation

13. Facts about
An average of 800 tornadoes are reported in the United States every year
Fastest tornado wind reported was 286 miles an hour in Wechita Falls Texas
The state that has the highest number of tornadoes a year is Texas with an average of 125

14. Myths about tornadoes
Highway overpasses are a safe place to shelter if driving on the road
Tornadoes never strike big cities
The part of the basement towards the approaching tornado is the safest

15. Fujita Scale
The Enhanced Fujita scale classifies tornadoes according to the damage they cause.
Scale Ranges from: F-0 to F-5
Created by Ted Fujita

16. FUJITA SCALE OF TORNADO INTENSITY
Rating Wind Speed Damage F mph Rips shingles off roofs; flips mobile homes.

17. FUJITA SCALE OF TORNADO INTENSITY
Rating Wind Speed Damage F mph Upturns and flips boxcars.

18. FUJITA SCALE OF TORNADO INTENSITY
Rating Wind Speed Damage F mph Exterior walls and roofs blown off homes. Metal buildings collapsed or severely damaged. Forests and farmland destroyed.

19. FUJITA SCALE OF TORNADO INTENSITY
Rating Wind Speed Damage F mph Few walls left standing. Large concrete blocks launched far distances.

20. FUJITA SCALE OF TORNADO INTENSITY
Rating Wind Speed Damage F mph Homes flattened with all debris removed. Schools, motels, and other larger structures damaged considerably with exterior walls and roofs gone. Top floors demolished.

21. F – 5 Tornado Destruction

22. Tornado Alley
The area of the United States in which tornadoes are most frequent. Tornado Alley includes the Mississippi, the Ohio, and lower Missouri River Valleys. Although no state is entirely free of tornadoes, they are most frequent in the Plains area between the Rocky Mountains and Appalachians.