Introducing Physical Geography (Wse)

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Chapter 7 Global Climates This chapter examines the major influences on atmospheric temperature and precipitation characteristics to explain the different global climates. The climate of an area based on the average weather conditions over an extended period of time as revealed by average measurements of temperature and precipitation. Important climate principles : Low latitude locations have warmer temperatures and smaller annual temperature ranges than high latitude locations. Continental locations tend to have much larger annual temperature ranges than coastal locations at the same latitude. Colder locations tend to have less precipitation than warm locations, because warm air can hold more moisture than cold air. The basic control on temperature is latitude, while the effect of a continental or maritime location is an important secondary control. Precipitation generalizations : Atmospheric circulation and the pressure systems it generates has a strong influence on global precipitation patterns. The equatorial region experiences high convectional precipitation because of excess heating. These areas of high precipitation extend north and south along the east sides of the continents because the trade winds bring moisture onto the land. The subtropical high-pressure cells, characterized by dry, subsiding air, produce arid and semiarid regions. Mountain ranges produce wet areas where air masses are forced to rise over the mountains creating an orographic effect. Coastal mountains also act as barriers to moisture producing a rainshadow effect on the lee side of the mountains. Continental interiors tend to be dry because they are far away from the source areas of moist air masses. Three types of annual precipitation patterns are: Seasonally uniform distributed precipitation Precipitation maximum during the warmest period of the year (high sun season) Precipitation maximum during the coolest period of the year (low sun season)
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Seven global precipitation regions : Wet equatorial Trade wind coasts Tropical Deserts Midlatitude deserts and steppes Moist subtropical Midlatitude west coasts Arctic and Polar Deserts Low latitude climates are dominated by cT, mT, and mE air masses. The position of the ITCZ and the subtropical high pressure cell affect these climates throughout the year. Weather disturbances include the easterly wave and tropical cyclones. This group of climates includes: Wet equatorial Monsoon and trade-wind coast Wet-dry tropical Dry tropical Midlatitude climates occupy the polar front zone where warm and cold air masses interact producing wave cyclones. This groups of climates includes: Dry subtropical Moist subtropical Mediterranean Marine west-coast Dry midlatitude Moist continental High latitude climates are dominated by polar and arctic air masses. They are sources areas of cP, mP, cA, and cAA air masses. Continental polar air meets cA air
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ch_07_sum_climates - Chapter 7 Global Climates This chapter...

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