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7th Grade Chapter 6 Lesson 4
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7th Grade Chapter 6 Lesson 4



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    7th Grade Chapter 6 Lesson 4 7th Grade Chapter 6 Lesson 4 Presentation Transcript

    • 7th Grade Chapter 6 Lesson 3
        • Pgs. 212 - 220
        • For Student Use Only
    • Global Winds
      • Wind:
        • Horizontal movement of air
      • Global Wind:
        • Covers parts of the earth’s surface, LARGE areas
        • Caused by uneven heating of Earth
          • Polar Areas- slanted sun, cooler
          • Tropical Areas- more direct sun, warmer
    • Global Winds
      • Poles:
        • Land temperature affects temperature of air and vice versa
          • Cool surface- cools
          • Warm surface-warms
        • Air travels from High pressure (polar) to Low pressure (equator)
    • Global Winds
      • Wind Zones:
        • Tropical Zone (0 to 30 N and S of equator): trade winds are found here, Northeast in Northern Hemisphere, Southwest in Southern Hemisphere
        • Temperate Zone (30-60 N and S of Equator): prevailing winds come from the west (both hemispheres), these winds are called the westerlies
        • Polar Zone (60-90 N and S of equator): prevailing winds come from east direction called Easterlies
    • Global Winds
      • Other Wind Zones:
        • ITCZ (Inter-Tropical-Convergence-Zone): where the trade winds meet at the equator (Hot air rising called Converging)
          • AKA- Doldrums- no horizontal wind and ships could get stuck
        • Horse Lattitudes (30 N and S of equator): winds are again vertical (sinking and called diverging), sailors used to have to dump horses
    • Global Winds
      • Winds:
        • Subtropical highs: Areas of high pressure air found within the horse lattitudes
      • Air Mass Behavior:
        • 2 different temperature air masses do not mix.
        • Polar Air meeting Subtropical air- do not mix
          • Called a Polar Front (warm air rises up cold air pushes underneath)
    • Global Winds
      • Winds:
        • Polar Highs:
          • High pressure areas in the polar regions
          • Air flows outwards from these regions
      • Circulation:
        • Winds move down and over
        • Inertia- the tendency of an object in motion to stay in motion the tendency of an object at rest to stay at rest until a force acts upon it
    • Global Winds
      • Wind Movement:
        • Coriolis Effect:
          • The spinning of the earth causes the winds to curve
          • All winds in the Northern Hemisphere curve right
          • All winds in the Southern Hemisphere curve left
        • Air Movement:
          • Air rushes to ITCZ and curves
          • Here it piles up and sinks (horse lattitudes)
          • As the winds flow out they curve
    • Global Winds
      • Winds:
        • Hadly Cell- circualtion of tropical air
        • Rosby Waves- upper troposphere waves (heating and cooling) of air
        • Jet stream- high atmosphere powerful wind current, can be as fast as 250 MPH
          • Subtropical Jet Stream- above sub-tropical areas
          • Polar front jet Stream- flows along the warm air in a polar front
          • Occur just below the tropopause (upper layer of troposphere)