1. Severe Weather!!!!!!! Chapter 20.3

2. The main types of severe weather are:
What is severe weather?
Weather that poses a danger.
The main types of severe weather are:
Thunderstorms
Tornadoes
Hurricanes

3. What is a thunderstorm? A storm that produces:
1. Lightning Thunder Heavy Rain and/or flooding Strong winds and possibly hail
They last about minutes.
Mr. Fetch’s Earth Science Classroom

4. How do thunderstorms form?
When warm, moist air is lifted up violently. The air rises up to form a cumulonimbus cloud.
Mr. Fetch’s Earth Science Classroom

5. If the winds are over 58 mph, the thunderstorm is said to be a SEVERE THUNDERSTORM

6. Mr. Fetch's Earth Science Class
How does lightning form?
Updrafts and downdrafts of wind and rain cause different parts of a cloud to become electrically charged. + + -
(+) charge at top of cloud
(-) charge at bottom of cloud -
Mr. Fetch's Earth Science Class

7. How Far Away is Lightning?
Every second between a lightning flash and thunder means the storm is 1 mile away.
Speed of Light: 186,000 miles/second or 300,000 km/second
Speed-of-sound: 1100 ft/sec (330 m/sec)

8. Struck By Lightning!!!
The odds of becoming a lightning victim in the U.S. in any one year is 1 in 100,000.
The odds of being struck in your lifetime is 1 in 3,000.

9. The Safest Place? https://www.youtube.com/watch?v=bKczulzP5wk
Talking on the telephone is the leading cause of lightning injuries inside the home
Standing under a tall tree is one of the most dangerous places to take shelter outside

10. NO SUCH THING AS HEAT LIGHTNING = FAR AWAY THUNDERSTORM
Lightning Facts
NO SUCH THING AS HEAT LIGHTNING = FAR AWAY THUNDERSTORM

11. Thunder
Caused by the rapid expansion and contraction of the air surrounding a lightning bolt.

12. How does a tornado form?
Tornado: A rotating column of air.
1. Wind shear causes air to rotate. 2. The rotating column of air is lifted by updrafts 3. The column of air touches the ground = tornado

16. Tornadoes are usually associated with severe thunderstorms.

18. How are tornados classified?

20. Interesting Tornado facts
3 out of every 4 tornadoes in the world happen in the United States
The United States have an average of 800 tornadoes every year
A Tornado can occur at any time, but most often between 3pm and 9pm
The chances that a tornado is a F5, the highest classification for a tornado on the F-scale, is less than 0.1%
A Tornado in Oklahoma once destroyed a whole motel. People later found the motel’s sign in Arkansas

21. Storm Chasing - your future career?

22. Hurricanes A tropical area of low pressure that forms over warm water
Wind speeds must be higher than 74 mph.
Usually given alphabetical names for convenience
Slow moving storm: Lasts for days.
Pushed by the easterly trade winds.

23. Hurricane Animation

24. 5 Things a Hurricane needs to Form

25. Progression to a Hurricane
Disturbance
Depression
Tropical Storm
Hurricane

26. Saffir-Simpson Scale is used to measure a hurricane’s intensity

27. Storm Surge – like what happened with Hurricane Katrina
Most dangerous part of hurricanes
Storm Surge – like what happened with Hurricane Katrina L