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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)