1. Severe Weather

2. Supercells Supercells are self-sustaining, extremely powerful storms
Supercells can last for several hours and have updrafts as strong as 150mph.
There is about 100,000 thunderstorms in the U.S. each year and 10% of them are severe.

4. Lightning
Lightning is a massive electrical discharge between clouds or a cloud and the ground
Lightning is caused by friction from the rapid rush of air in a cumulus cloud
Lightning carries about 100 million volts of electricity and heats the surrounding air to about 30,0000C.

6. Thunder
Thunder is sound produced as superheated air rapidly expands and contracts.
You may see lightning well before you hear thunder because light travels faster than sound even though they are produced at the same time.

7. Wind
Violent downdrafts that are concentrated to a local area are downbursts.
Macrobursts can destroy an area 3 miles wide and have wind speeds more than 125mph.
Microbursts can destroy an area less than 2 miles wide and can have winds exceeding 155mph.

10. Hail Hail is precipitation in the form of balls or lumps of ice.
Hail forms when ice gets caught in strong updrafts and continues to get larger.

12. Tornadoes
A tornado is a violent, whirling column of air in contact with the ground.
Tornadoes are called funnel clouds before they touch the ground.

13. Tornado Classification
Tornadoes are classified according to the Enhanced Fujita scale.
The scale ranges from EF0 to EF5.
Weak tornadoes (EF0 and EF1)
80% of all tornadoes
Path: up to 3 miles

14. Tornado Classification
Weak tornadoes (EF0 and EF1)
80% of all tornadoes
Path: up to 3 miles
Wind speed: 60 to 155mph
Duration: 1-10 min

15. Tornado Classification
Strong tornadoes (EF2 and EF3)
19% of all tornadoes
Path: up to 15 miles
Wind speed: 110 to 205mph
Duration: 20+ min

16. Tornado Classification
Violent tornadoes (EF4 and EF5)
1% of all tornadoes
Path: up to 50 miles
Wind speed: over 200mph
Duration: over 1 hour

17. There are more tornadoes in the U.S. than anywhere else in the world.
The majority of those tornadoes in the U.S. occur in region called “Tornado Alley” which extends through Texas, Oklahoma, Kansas, and Missouri.