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Weather

Weather. Ch. 20. Thunderstorms & Tornadoes sec. 3. How large are storms? Storms come various sizes. largest (~2000 km) mid-latitude storms (ex. low-pressure systems) medium (100s of km) hurricanes smallest (a few km) thunderstorms

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Weather

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  1. Weather Ch. 20

  2. Thunderstorms & Tornadoes sec. 3 • How large are storms? • Storms come various sizes. • largest (~2000 km) • mid-latitude storms (ex. low-pressure systems) • medium (100s of km) • hurricanes • smallest (a few km) • thunderstorms • Is storm size a good indicator of the damage it can cause? • No • thunderstorm  tornado • mid-latitude low  rain or snow.

  3. Tornadoes • What is a tornado? • violently rotating column of air • usually touches the ground • What do tornadoes look like? • often vortex or funnel-shaped cloud (w/ flying debris) • can also be: • rope shaped • wedge shaped • w/ more than one vortex

  4. Brain Pop: Tornadoes Tornadoes • How do tornadoes form? • rotating updraft (mesocyclone) forms • air pressure at center: very low • air sucked in expands & cools • water vapor condenses & wall cloud may become visible @ base of storm • If air is drier or pressure is higher, cloud may contain dust & debris • creates loud roaring sound

  5. Tornadoes • When & where do tornadoes form? • anywhere & at any time of year • MOSTLY in “Tornado Alley” (Texas northward to South Dakota) in spring & early summer

  6. Tornadoes • How is the intensity of a tornado measured? • Fujita scale • F0 (weakest) to F5 (most violent) • What are the effects of tornadoes?

  7. Tornadoes • Predicting formation & path is difficult. • Why? • b/c destructive & often unpredictable • can damage instruments • can put people in danger • Improvements have been made. • conventional radar  map precipitation • Doppler radar  identify which way winds are moving w/in storm • can identify a rotating mesocyclone & give people ~20 min advance warning

  8. Tornadoes • What is the difference between a tornado watch & warning? • watch  tornado MAY form • warning  tornado spotted

  9. Hurricanes & Winter Storms sec. 4 • What is the difference between a hurricane, typhoon, & cyclone? • location • Atlantic • hurricane • Pacific • typhoon • Indian • cyclone

  10. Hurricanes • What is a hurricane? • a large rotating storm of tropical origin that has sustained winds of at least 119 km/hr (74 mph) • What is the pressure like at the center of a hurricane? • very low (Sandy… lowest pressure for any storm to hit north of North Carolina  940 millibars or 27.76 inches)

  11. Brain Pop: Hurricanes Animated Guide: Hurricane Hurricanes • How do hurricanes form? • in tropics a mild atmospheric disturbance causes humid air to rise • more water condenses & releases heat • continues as long as humid air is available & rising • to become a hurricane, it must begin to rotate (counterclockwise in the N. Hemi. due to Coriolis Effect)

  12. Hurricanes • What determines the path of a hurricane? • global wind patterns • In Atlantic (N. Hemi.) generally move west or northwest. • Then, often curve north (and may eventually head east). • actual paths can vary considerably… • shown by cone of uncertainty

  13. Hurricanes • What are some of the effects of hurricanes? • wind damage • inland flooding • storm surge • large wave of water from strong winds of eye wall • blow water into a dome • waves • coastal erosion

  14. Hurricanes • When is hurricane season in the U. S.? • June 1 – November 30 • What’s the diff. between a hurricane watch & warning? • watch  hurricane expected to arrive w/in 24-36 hours • warning  hurricane expected to w/in 24 hours or less

  15. Hurricanes • How do scientists classify tropical storms/hurricanes? • by wind speed • tropical depression  up to 61 km/hr • tropical storm  61 – 119 km/hr • hurricane  119+ km/hr • use Saffir-Simpson scale to rate strength

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