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Download Chapter 6. Biogeography: Climate, Biomes and Terrestrial Biodiversity
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Chapter 7. Climate and Terrestrial Biodiversity Living in the Environment 16th Edition www.wral.com/weather What is weather? Short-term set of physical properties of the troposphere at a particular place and time. Temperature Pressure Humidity Precipitation Sunshine Cloud cover Frontal Weather What are Highs and Lows? changes in atmospheric pressure • High – Air mass with high pressure – Cool, dense air descends toward the earth’s surface and becomes warmer • Low – Air mass with low pressure – Less dense warm air spirals inward – The center of a low rises, and its warm air expands and cools Highs and Lows Weather Extremes • Tornadoes • Tropical cyclones Atlantic Ocean = hurricanes Pacific Ocean = typhoons Descending cool air Severe thunderstorms can trigger a number of smaller tornadoes Severe thunderstorm Rising warm air Tornado forms when cool downdraft and warm updraft of air meet and interact Rising updraft of air Tropical Cyclones Rising winds exit from the storm at high altitudes. The calm central eye usually is about 24 kilometers (15 miles) wide. Gales circle the eye at speeds of up to 320 kilometers (200 miles) per hour. Moist surface winds spiral in towards the center of the storm www.wral.com/weather Prince William Sound Gulf of Alaska Risk of Tornadoes CANADA Highest High Medium Low UNITED STATES Grand Banks Tropical Cyclone Frequency High Moderately high MEXICO Atlantic Ocean Climate is Climate the average weather patterns for an area over a long period of time (30 - 1,000,000 years). and It is determined by its Average Precipitation effects and Average Temperature which are influenced by latitude altitude ocean currents and affects where people live how people live what they grow and eat Global Air Circulation Patterns Result In: 1) Uneven heating of the earth’s surface. 2) Seasonal changes in temperature and precipitation. 3) Rotation of the earth on its axis • Deflect winds Six convection cells (3N/3S) Cold Cool Temperate Warm Temperate Tropical (equator) Tropical Warm Temperate Cool Temperate Cold Climate type 23.5º Winter (northern hemisphere tilts away from sun) Spring (sun aims directly at equator) Solar radiation Fall (sun aims directly at equator) Summer (northern hemisphere tilts toward sun) © 2004 Brooks/Cole – Thomson Learning Easterlies (from the east) Westerlies (from the west) 60 N Northeast tradewinds 30 N (Doldrums) equator Southeast tradewinds 30 S Westerlies 60 S Initial pattern of air circulation Easterlies Deflections in the paths of air flow near the earth’s surface Global Air Circulation Patterns Result In: 4) Long term variation in the amount of solar energy • Wobbles and tilts about the earth’s axis. 5) Properties of air and water • Convection Cells – circulate air, heat, and moisture both vertically and from place to place. LOW PRESSURE Heat released radiates to space HIGH PRESSURE Cool, dry air Condensation and precipitation Falls, is compressed, warms Rises, expands, cools Warm, dry air Hot, wet air Flows toward low pressure, picks up moisture and heat HIGH Moist surface warmed by sun LOW PRESSURE PRESSURE Cold, dry air falls Cell 3 North Polar cap Arctic tundra Evergreen coniferous forest 60 Temperate deciduous forest and grassland Desert 30 Cell 2 North Cool, dry air falls Cell 1 North Tropical deciduous forest 0 Equator Tropical rain forest Tropical deciduous forest Cell 1 South 30 60 Desert Temperate deciduous forest and grassland Cool, dry air falls Cell 2 South Polar cap Cold, dry air falls Relationship between global air circulation and biomes Moist air rises — rain Moist air rises — rain Cell 3 South Moist air rises, cools, and releases moisture as rain Solar radiation Convection cell Cool Warm current Cool current air Equator Warm air Warm water Warm current Cool current Polar front Surface Currents Midlevel currents Bottom Currents Cold water Ocean Currents Polar (ice) Warm temperate Highland Warm ocean current Subarctic (snow) Dry Major upwelling zones Cold ocean current Cool temperate Tropical River Movement of surface water Wind Diving birds Fish Upwelling Zooplankton Phytoplankton Nutrients A shore upwelling What is the El Nino-Southern Oscillation (ENSO)? 1) Occurs in the Pacific Ocean 2) Prevailing westerly winds weaken or cease 3) Surface water along the South and North America coasts become warmer 4) The normal upwelling of cold, nutrient rich water are suppressed Surface winds blow westward EQUATOR AUSTRALIA Warm waters pushed westward SOUTH AMERICA Warm water Thermocline Cold water Normal Conditions Winds weaken, causing updrafts and storms Drought in Australia and Southeast Asia EQUATOR AUSTRALIA Warm water flow stopped or reversed SOUTH AMERICA Warm water deepens off South America Warm water Thermocline Cold water El Niño Conditions El Niño Drought Unusually high rainfall Unusually warm periods the greenhouse effect Major Greenhouse Gases 1) Water vapor H2O 2) Carbon dioxide CO2 3) Methane CH4 4) Nitrous oxide N2O 5) Chlorofluorocarbons CFCs a Winds carry moisture inland from Pacific Ocean b Clouds, rain on windward side of mountain range c Rain shadow on leeward side of mountain range Dry habitats Moist habitats the rain shadow effect Rain Shadow Effect Cool air descends Land warmer than sea; breeze flows onshore Sea Breeze Warm air ascends Cool air descends Warm air ascends Land cooler than sea; breeze flows offshore Land Breeze
