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Chapter 9 The Global Scope of Climate Climatic Classification ` ` ` Latitude – Pole-to-Equator temperature gradient Continentality – Proximity to large bodies of water Seasonality – Changes in patterns during the annual cycle Climatic Classification ` A scheme for dividing characteristic climate types ` Begun with the Ancient Greeks Frigid Zone Temperate Zone Torrid Zone the (60°-90°N) (30°-60°N) ( 0°-30°N) world into Climatic Classification ` Köppen-Geiger-Pohl System Air temperature and precipitation Vegetation regimes ` Thornthwaite System Air temperature and precipitation Climatic water balance ` Terjung System Net radiation Energy balance Köppen-Geiger-Pohl System The Climatic Water Balance A system of water accounting Input: Precipitation The Climatic Water Balance A system of water accounting Output: Evaporation The Climatic Water Balance A system of water accounting ` Evaporation – process by which water becomes a gas The Climatic Water Balance A system of water accounting Output: Transpiration The Climatic Water Balance A system of water accounting ` ` Evaporation – process by which water becomes a gas Transpiration – evaporative loss of water to the atmosphere through the stomata of leaves The Climatic Water Balance A system of water accounting ` Evapotranspiration – combined loss of water to the atmosphere by evaporation from the soil and transpiration from plants The Climatic Water Balance A system of water accounting Output: Evapotranspiration The Climatic Water Balance A system of water accounting Output: Runoff/Streamflow The Climatic Water Balance A system of water accounting P = ET + R The Climatic Water Balance Potential Evapotranspiration Ideal rate of evapotranspiration that occurs when a complete canopy of growing plants is continuously supplied with all the soil water they need. The Climatic Water Balance Potential Evapotranspiration ` ` Is largely a function of air temperature Greatest in the tropics; Least at the poles The Climatic Water Balance Precipitation Moisture Supply vs. Potential Evapotranspiration Moisture Demand The Climatic Water Balance Classification of Climate ` Latitude Low-latitude Climates ( 0°-30°N) – 4 Mid-latitude Climates (30°-60°N) – 6 High-latitude Climates (60°-90°N) – 3 ` Seasonal Supply vs. Demand Seasonality Continentality Chapter 10 Low-Latitude Climates Low-Latitude Climates ` Dominated by the circulation of the Hadley Cells Low-Latitude Climates ` Dominated by the circulation of the Hadley Cells seasonal migration of the ITCZ Low-Latitude Climates ` Dominated by the circulation of the Hadley Cells seasonal migration of the ITCZ prevailing easterly trade winds Low-Latitude Climates ` Dominated by the circulation of the Hadley Cells seasonal migration of the ITCZ prevailing easterly trade winds ` Characterized by a relatively temperature regime all year long uniform Consequently, potential evapotranspiration nearly constant all year long air is Potential Evapotranspiration – Low-Latitudes 1) Wet Equatorial Climate ` ` ` Associated with the ITCZ all year long mE air mass dominates, some mT Rainfall is plentiful during the entire year Annual total exceeds 250 cm ` Air temperature is relatively uniform Mean air temperature near 27°C Wet Equatorial Climate Wet Equatorial Climate Iquitos, Peru – 3°S 2) Dry Tropical Climate ` ` ` Descending air of the Hadley Cell Sub-tropical High Pressure dominates Little rainfall during the entire year Desert environment ` Air temperature has a slight seasonal trend Greatest air temperatures during the high-sun season Dry Tropical Climate Dry Tropical Climate Wadi Halfa, Sudan -- 22°N 3) Tropical Wet & Dry Climate ` ` ` Seasonal migration of the ITCZ Sub-tropical High Pressure in low-sun season; mE in high-sun season Marked seasonal cycle to precipitation Precipitation “follows the sun” ` Air temperature has a slight seasonal trend Greatest air temperatures during the high-sun season Tropical Wet & Dry Climate (N.H.) Tropical Wet & Dry Climate (S.H.) Tropical Wet & Dry Climate Timbo, Guinea -- 10°N Tropical Wet & Dry Climate 4) Trade-Wind Coastal Climate ` ` ` East coasts – windward side of the continent Monsoon climate – wind shift during year Marked seasonal cycle to precipitation Precipitation “follows the sun” ` Air temperature has a slight seasonal trend Greatest air temperatures during the high-sun season Trade-Wind Coastal Climate (N.H.) Trade-Wind Coastal Climate (S.H.) Trade-Wind Coastal Climate Belize City, Belize, Sudan -- 17°N Trade-Wind Coastal Climate Cochin, India -- 10°N Low-Latitude Climates Chapter 11 Mid-Latitude and High-Latitude Climates The Climatic Water Balance Classification of Climate ` Latitude Low-latitude Climates ( 0°-30°N) – 4 Mid-latitude Climates (30°-60°N) – 6 High-latitude Climates (60°-90°N) – 3 ` Seasonal Supply vs. Demand Seasonality Continentality Mid-Latitude Climates Mid-Latitude Climates ` Dominated by the prevailing westerlies Primarily Northern Hemisphere climates West-to-east movement of cyclones and fronts ` ` Latitude is a secondary factor Consists of six climate types Three in the lower mid-latitudes – subtropics Three in the upper mid-latitudes Mid-Latitude Climates Potential Evapotranspiration – Subtropics 1) Dry Subtropical Climate ` ` ` ` Extension of the Dry Tropical climate into midlatitudes Source region for cT air masses Distinct cool season occurs during winter Low precipitation all year long Dry Subtropical Climate Dry Subtropical Climate Dry Subtropical Climate Yuma, Arizona – 33°N 2) Moist Subtropical Climate ` ` ` ` ` Flow of air from mT from the western edge of the subtropical High pressure Strong annual air temperature cycle with no winter month averaging below freezing Abundant rainfall all year long; cyclonic in winter, convectional in summer High humidity “Hurricane Coast” Moist Subtropical Climate Moist Subtropical Climate Moist Subtropical Climate Moist Subtropical Climate, Charleston, South Carolina – 33°N Moist Subtropical Climate Effect of the Subtropical High 3) Mediterranean Climate Mediterranean Climate ` ` ` ` Dominated by the influence of cT air in summer, mT air in winter Strong High pressure offshore in summer deflects storm tracks to the north Moderate temperature range with warm to hot summers and mild winters Wet winter and dry summer Æ Seasonal Mediterranean Climate Mediterranean Climate Monterey, Californa – 36°N Mediterranean Climate Subtropical Climates Potential Evapotranspiration – Upper Mid-latitudes Upper Mid-Latitude Climates 4) Marine West Coast Climate ` ` ` Dominated by mP air masses and onshore flow of moist air from the westerlies Temperature cycle moderated by marine influence of warm, offshore ocean current – cool summers, mild winters Abundant precipitation, often with a winter maximum and usually accentuated by orographic effects Marine West Coast Climate Marine West Coast Climate Marine West Coast Climate, Vancouver, British Columbia – 49°N Upper Mid-Latitude Climates 5) Dry Midlatitude Climate ` ` ` Dominated by dry cP air masses Strong air temperature cycle with large annual range – summers are warm to hot, winters are cold and snowy Little precipitation due to the rainshadow effect and interior continental location – slight summer maximum Dry Midlatitude Climate Dry Midlatitude Climate Dry Midlatitude Climate, Pueblo, Colorado – 38°N Upper Mid-Latitude Climates 6) Moist Continental Climate ` ` ` Dominated by frontal interactions between dry cP and moist mT air masses Summers warm, winters cold; relatively large annual air temperature range Ample precipitation with a slight summer maximum – convective in summer; cyclonic in winter Moist Continental Climate Moist Continental Climate Moist Continental Climate, Madison, Wisconsin – 43°N Moist Continental Climate Upper Midlatitude Climates Moist Continental Climate Midlatitude Climates High-Latitude Climates High-Latitude Climates ` Dominated by the Arctic Air Mass Primarily Northern Hemisphere climates One, however, is present in the Southern Hemisphere – in Antarctica (dominated by the Antarctic Air Mass) High-Latitude Climates ` Dominated by the Arctic Air Mass Primarily Northern Hemisphere climates Also found along the tip of Antarctica near Chile (dominated by Antarctic Air Mass) ` Consists of only three climate types, stratified primarily by latitude and proximity to the coast Potential Evapotranspiration – High-Latitudes 1) Continental Subarctic Climate ` ` ` ` ` Associated with Boreal Forest vegetation Short, cool summer – long, very cold winter Greatest Annual Air Temperature Range Source region for cP air masses – located mainly in the continental interiors Little rainfall, falling mostly in the summer Continental Subarctic Climate Continental Subarctic Climate Fort Vermillion, Alberta – 57°N Continental Subarctic Climate Continental Subarctic Climate Yatkutsk, Russia – 61°N 2) Tundra Climate ` ` ` ` Coastal Arctic fringe climate Maritime influence keeps winter warmer than Continental Subarctic Very short summer, very long winter Low annual precipitation total Tundra Climate Tundra Climate Upernivik, Greenland – 73°N Tundra Climate Tundra Climate Barrow Point, Alaska – 71°N 3) Ice Sheet Climate ` ` ` ` Source region for cA and cAA air masses All months are below freezing – no growth Lowest Global Air Temperatures Polar deserts – very low precipitation totals although snow accumulates Ice Sheet Climate Ice Sheet Climate Ice Sheet Climate High Latitude Climates Climate and Ocean Currents Hypothetical Northern Hemisphere Continent Climate and Surface Winds Hypothetical Northern Hemisphere Continent Climate, Ocean Currents, and Surface Winds Hypothetical Northern Hemisphere Continent