III. TornadoesIII. Tornadoes

A. Introduction

1. Tornado- A whirling funnel-shaped cloud 1. Tornado- A whirling funnel-shaped cloud that touches the groundthat touches the ground

2. Water spout- a tornado that forms over a 2. Water spout- a tornado that forms over a body of waterbody of water

3. Time/Tornado Size3. Time/Tornado Sizea. They last about 15 minutesa. They last about 15 minutesb. Only a few hundred meters acrossb. Only a few hundred meters across

B. How Tornadoes FormB. How Tornadoes Form1.1. Tornadoes form in low, heavy cumulonimbus Tornadoes form in low, heavy cumulonimbus

clouds (the same clouds that form severe clouds (the same clouds that form severe thunderstorms)thunderstorms)

2.2. When severe cold fronts formWhen severe cold fronts forma.a. Maritime tropical and continental polar air Maritime tropical and continental polar air

masses collidemasses collideb.b. When these air masses collide the updrafts When these air masses collide the updrafts

spiral past downdraftsspiral past downdrafts

3. Location3. Locationa. More tornadoes in the United States than in any a. More tornadoes in the United States than in any other countryother countryb. The Great Plains (between the Mississippi River & b. The Great Plains (between the Mississippi River & the Rocky Mountains)the Rocky Mountains)c. Tornado Alley- Texas, Oklahoma, Kansas & c. Tornado Alley- Texas, Oklahoma, Kansas & Nebraska Nebraska

4. Time of Year- Tornadoes 4. Time of Year- Tornadoes frequently occur in the frequently occur in the spring and early summer,spring and early summer, but can occur any time but can occur any time of yearof year

C. Tornado SafetyC. Tornado Safety1.1. Cause of the DamageCause of the Damage

a.a. Strong windsStrong windsb.b. Flying debrisFlying debris

2.2. Watches and WarningsWatches and Warningsa.a. Watch- a tornado is possible Watch- a tornado is possible b.b. Warning- a tornado has been spottedWarning- a tornado has been spotted

3. Safest Place to be3. Safest Place to bea. BEST- the basement of a well built buildinga. BEST- the basement of a well built buildingb. NEXT BEST- interior rooms away from b. NEXT BEST- interior rooms away from windowswindows

D. Additional InformationD. Additional Information1.1. Vortex- a spiraling column of fluid around a Vortex- a spiraling column of fluid around a

central axiscentral axis2.2. Scale used to measure TornadoesScale used to measure Tornadoes

a.a. Fujita Scale or Enhanced Fujita ScaleFujita Scale or Enhanced Fujita Scaleb.b. Based on damage and wind speedBased on damage and wind speed

3.3. Wind Speed- F1 minimum wind speed of 73 Wind Speed- F1 minimum wind speed of 73 mph (EF0- 65mph)mph (EF0- 65mph)

4.4. Speed of Tornado- stationary to over 60 Speed of Tornado- stationary to over 60 mphmph

Good tornadoes with debris clouds: http://www.youtube.com/user/NationalGeographic?feature=relchannel#p/search/0/43VoMesUd2Q

Tornado Flips Cars: http://www.youtube.com/watch?v=LugFE3oRaN0

Storm Chasers: http://www.youtube.com/watch?v=a_MuaWDg5Z0

Waterspout Forming: http://www.youtube.com/watch?v=zpCPH---ib4