Global winds are caused by the uneven heating of the Earth's surface by the sun. This causes air to move from areas of high pressure to low pressure. There are three main wind zones: the tropical zone near the equator dominated by trade winds, the temperate zone between 30-60 degrees dominated by westerlies, and the polar zone above 60 degrees dominated by easterlies. Within these zones, the Coriolis effect causes winds in the Northern Hemisphere to curve right and winds in the Southern Hemisphere to curve left.

1. 7th Grade Chapter 6 Lesson 3 Pgs. 212 - 220 For Student Use Only

2. 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

3. 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)

4. 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

5. 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

6. 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)

7. 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

8. 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

9. 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)