SEVERE WEATHER CHAPTER 20 3 What is severe

SEVERE WEATHER!!!!!!! CHAPTER 20. 3

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

What is a thunderstorm? A storm that produces: 1. Lightning 2. Thunder 3. Heavy Rain and/or flooding 4. Strong winds and possibly hail They last about 15 -60 minutes. Mr. Fetch’s Earth Science Classroom

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

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

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

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)

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. https: //www. youtube. com/watch? v=L 1 Hh. RAUq. Fq. M https: //www. youtube. com/watch? v=lt. K 5 c 60 n. BHQ

The Safest Place? 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 https: //www. youtube. com/watch? v=b. Kczulz. P 5 wk

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

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

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

Tornadoes are usually associated with severe thunderstorms.

How are tornados classified?

INTERESTING TORNADO FACTS 3 out of every 4 tornadoes in the world happen in the United States A Tornado can occur at any time, but most often between 3 pm and 9 pm The United States have an average of 800 tornadoes every year A Tornado in Oklahoma once destroyed a whole motel. People later found the motel’s sign in Arkansas The chances that a tornado is a F 5, the highest classification for a tornado on the F-scale, is less than 0. 1%

Storm Chasing - your future career? http: //www. youtube. com/watch? v=bh. GWWY 1 n. CWw&feature=relmfu

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

Hurricane Animation http: //www. cbsnews. com/htdocs/natural_disasters/hurricanes/fram esource_flash. html

5 Things a Hurricane needs to Form

Progression to a Hurricane Disturbance Depression Tropical Storm Hurricane

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

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