Lecture XII – Global Physical Ecology

Lecture XII – Global Physical Ecology -...

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Lecture XII –Global Physical Ecology
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Global Environment Solar energy is the primary determinant of global patterns in temperature and precipitation by affecting the atmosphere, oceans, and land masses. Variation in the temperatures and precipitation across the earth affect the distribution of biomes and species that comprise them.
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Global Variations in Solar Radiation Because of the shape of the earth, different regions of the globe are at different distances and angles to the sun This results in a pole-to-equator increasing gradient in solar radiation
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Seasonal Variation in Solar Radiation Because of the 23.5° tilt in the earths’ axis, the distance and angle of the two hemispheres changes as the earth orbits the sun This causes seasonal variation in solar radiation
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Variation in Regional Temperatures Direct solar radiation is the primary determinant of temperature at large scales on the earth Therefore, there is a pole-to-equator increase in temperature, as well as seasonal variation in temperature However, neither the temperature nor the variation is equal across the globe; in fact, there are marked differences between the northern and southern hemispheres
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Variation in Global Temperatures The range and variation in temperatures is greater in the northern than in the southern hemisphere This is dues to the larger proportion of landmass in the northern hemisphere
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Global Patterns in Air Movement At the equator the air is warmed by solar radiation, causing it to expand and rise Air that rises is replaced by air moving in from the north and south.
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Global Patterns in Air Movement As the air rises higher in the atmosphere it cools The cooler air sinks back to the earth at higher latitudes (about 30° N and S)
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Global Patterns in Air Movement This cycle of warm, air rising and cool air sinking, sets up large convection cells, called Hadley cells
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Global Patterns of Precipitation There are similar convection cells in the temperate and polar regions.
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Global Wind and Rain Patterns The convergence of the Hadley Cells at the equator produce areas of high rainfall, called the Intertropical Convergence Zone . Because of the seasonal patterns caused by the tilt of the earth, the ICZ moves north and south with the sun, thus creating seasonality in rainfall
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Global Patterns in Air Movement The air flowing back towards the equator from 30° N in the Hadley cells forms prevailing winds that are subject to the frictional forces of the rotating earth
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Global Patterns in Air Movement This force tends to deflect the winds to the right in the northern hemisphere and to the left in the southern hemisphere (Coriolis effect)
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Global Patterns in Air Movement The net result is the Northeast Trade Winds in the tropical areas of the northern hemisphere and the Southeast Trades in the South.
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Lecture XII – Global Physical Ecology -...

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