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Do Now: Read the Case study Write down three take-aways from the case study Core Case Study Blowing in the Wind: A Story of Connections • Wind connects most life on earth. – Keeps tropics from being unbearably hot. – Prevents rest of world from freezing. Figure 5-1 Factors Contributing to local climate: • • • • • • Solar radiation Earth’s rotation and path around the sun Air circulation Land masses and bodies of water Circulation of ocean currents Elevation of land masses 4 Major Factors affecting global air circulation • 1.) uneven heating of the earth’s surface by the sun • 2.) seasonal changes in temperature and precipitation. • 3.) rotation of the earth on its axis • 4.) Properties of air, water, and land 1.) uneven heating of the earth’s surface by the sun • Picture shining a flashlight on a soccer ball 2.) seasonal changes in temperature and precipitation. • The earth’s axis is tilted. • Northern and southern regions are either tilted towards or away from the sun. • This creates opposite seasons in the northern and southern hemispheres. Spring (sun aims directly at equator) Winter (northern hemisphere tilts away from sun) 23.5 ° Solar radiation Summer (northern hemisphere tilts toward sun) Fall (sun aims directly at equator) Fig. 5-3, p. 102 3.) rotation of the earth on its axis • As the earth rotates around its north-south axis, its equator spins faster than it’s polar regions. • As a result heated air masses rise above the equator and winds moving north and south eventually are deflected to the east and west. • Coriolis effect. Coriolis effect • The direction of air movement in the resulting atmospheric regions called cells sets up belts of prevailing winds. • Prevailing winds- major surface winds that blow almost continuously and distribute air, moisture, and dust over the earth’s surface. 4.) Properties of air, water, and land • Heat from the sun evaporates ocean water and transfers heat from the oceans to the atmosphere • Cyclical Convection Cells- circulate air, heat, moisture vertically and from place to place in the troposphere LOW PRESSURE Heat released radiates to space Cool, dry air Falls, is compressed, warms HIGH PRESSURE Condensation and precipitation Rises, expands, cools Warm, dry air Hot, wet air Flows toward low pressure, picks up moisture and heat HIGH PRESSURE Moist surface warmed by sun LOW PRESSURE Fig. 5-5, p. 103 Convection Cells • Heat and moisture are distributed over the earth’s surface by vertical air currents, which form six giant convection cells at different latitudes. Cold deserts Westerlies Northeast trades Forests Hot deserts Forests Equator Southeast trades Westerlies Hot deserts Forests Cold deserts Fig. 5-4, p. 102 Cell 3 North Cold, dry air falls Moist air rises — rain Polar cap Arctic tundra Cell 2 North Evergreen 60° coniferous forest Temperate deciduous forest and grassland Cool, dry air falls 30° Tropical Desert deciduous forest 0° Equator Cell 1 North Moist air rises, cools, and releases Moisture as rain Tropical rain forest Tropical deciduous forest 30° 60° Desert Temperate deciduous forest and grassland Cool, dry air falls Cell 2 South Polar cap Cold, dry air falls Cell 1 South Moist air rises — rain Cell 3 South Fig. 5-6, p. 103
