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9th Grade Chapter 3 Lesson 4
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9th Grade Chapter 3 Lesson 4



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    9th Grade Chapter 3 Lesson 4 9th Grade Chapter 3 Lesson 4 Presentation Transcript

    • 9 th Grade Chapter 3 Lesson 4 Pgs. 67-73 For Student Use Only
    • Storms
      • Lightning:
        • Lightning- abrupt discharge of electricity through the air
          • Lightning occurs when large amount of static electricity build up in cumulonimbus clouds (perhaps because of friction between ice crystals)
          • The cloud has a different charge from the ground and opposite charges attract
            • Air insults the two charges (keeps them apart)
    • Storms
      • Lightning:
        • Lightning
          • A stream of electrons (negative charged particles) goes from cloud to ground in a jerky pattern- this is called a stepped leader.
          • A positive stream of atoms reaches up to meet the stepped leader (usually from the tallest object around)
          • Return Stroke- (Positive and Negative meet)- electrons flow downward in a mighty current from cloud to ground
    • Storms
      • Lightning:
        • Lightning releases massive amounts of electricity and heats the surrounding air
        • Thunder- is a result of lightning heating the air
          • Thunder- is the explosive shockwave of sound from the rapidly expanding air
    • Storms
      • Lightning:
        • Types of Lightning:
          • Cloud to Ground Lightning: moves from cloud to ground
          • Cloud to Cloud Lightning: moves from cloud to cloud
          • Ground to Cloud Lightning: moves from ground to cloud
          • Heat Lightning: in summer when lightning from high altitude clouds is reflected over the horizon
          • Ball Lightning: rare phenomenon- incandescent sphere of electricity that floats in the air (not well understood)
          • Superbolt- Rare positive cloud to ground lightning
          • Hot Lightning: steady streams of electricity not a series of pulses (usually catches what it strikes on fire)
    • Storms
      • Tornado:
        • Tornado- narrow funnel of rapidly whirling winds
          • Smallest but most violent storms
          • Make a distinctive roaring, hissing noise
        • Tornado Formation:
          • Tornado Alley- Mississippi Valley and Eastern Great Plains has the most tornadoes
          • Formed when: a low pressure system where a mass of cold dry air clashes with a mass of warm, moist air
    • Storms:
      • Tornado Dangers:
        • The wind is the most dangerous thing in a tornado
        • Wind can be from 20 -150 mph
        • Tornadoes are unpredictable
      • Tornado Cousins
        • Waterspouts- tornado over water (weaker)
        • Dust Devil- small funnel-like winds (winds up to 45 mph)
    • Storms
      • Hurricanes:
        • Hurricane- giant whirling storms accompanied by destructive winds, torrential rains, high waves and tides.
        • Winds can be 74-200 mph
          • Scientific Name for Hurricane:
            • Tropical Cyclone
    • Storms
        • Other names for hurricanes:
          • Typhoons
          • Willy-Willies
          • Baguios
          • Cyclones
      • How Hurricanes Form:
        • Need 2 Things
          • Warm Oceans
          • Strong Coriolis
    • Storms
      • Hurricanes
        • Start with tropical disturbance
          • Tropical Disturbance: a thunderstorm over a tropical sea
          • Tropical Depression: when enough warm air (“fuel”) has been added and the rotating winds reach a sustained 23 mph
          • Tropical Storm: when winds reach 39 mph (it is given a name at this point)
          • Hurricane- when winds reach 74 mph
    • Storms
      • Hurricanes:
        • Categories:
          • 1= weakest
          • 2= weak
          • 3= This is a major hurricane
          • 4= Strong hurricane
          • 5= Strongest hurricane ever recorded
    • Storms
      • Hurricane Structure:
        • Eye: Center of the hurricane- a region of low pressure
        • Eye Wall: the cylinder of thick whirling clouds and rain that surround the eye
        • Rain Bands: lines of thunderstorms at lower altitudes
    • Storms
      • Hurricanes
        • Hurricanes stay strong if over water, but once they hit land they weaken
      • Dangers of Hurricane:
        • Winds
        • Floods- winds and low pressure push water towards land
        • Storm Surge- elevated water levels due to low pressure and winds