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Part 6. Current, Past, and Future Climates. Chapter 15 Earth’s Climates. Introduction. Climate is the long-term statistical properties of the atmosphere for an area
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Part 6. Current, Past, and Future Climates Chapter 15 Earth’s Climates
Introduction • Climate is the long-term statistical properties of the atmosphere for an area • Climate classifications are based on properties such as temperature, precipitation, air mass types, and water budget characteristics
The Koeppen climate classification system • Most widely used classification scheme • Based on natural vegetation types as indicators of average weather
Tropical Climates • Warm annual temperatures and minimal seasonal temperature variation • Differentiated on precipitation variations • Tropical Wet (Af) • Even precipitation through year • High humidity • Temperatures • Highs = low 30°s C (80°s F) • Lows = low 20°s C (70°s F)
Af climographs Monsoonal effects seen in the precipitation trends throughout the year
Monsoonal (Am) • Near tropical coastal areas • Monthly precipitation variations are significant, with very high annual totals • Small annual temperature variations
Am climographs (strong monsoonal precipitation)
Tropical Wet and Dry (Aw) • Poleward tropical margins • Distinct temperature and precipitation seasonality • Low sun dry period • Unreliable precipitation • Sahel region • Savanna vegetation
Dry Climates • 30% of Earth’s land surface • Defined by water balance • Potential evapotranspiration > precipitation • Subtropical Deserts (BWh) • Largest deserts • Western sides of continents • Areas with atmospheric subsidence • High diurnal temperature ranges (low dew points/humidity)
High precipitation variability of BWh regions Southern California site; 1983 and 1992 were El Nino years
Subtropical Steppe (BSh) • High aridity • High precipitation and temperature variability • Large temperature ranges • Extreme summer temperatures • Summer precipitation
Mid-Latitude Deserts (BWk) • Extreme continentality and/or rain shadows • Asia and the Western U.S. • Very high temperature ranges • Summer temperatures – very hot • Nighttime and winter temperatures - very cool • Higher humidity and precipitation
Mid-Latitude Steppe (BSk) • A transition zone • Higher annual average precipitation than true desert
Mild Mid-Latitude Climates • Eastern continental areas • Varying precipitation regimes • Mild winter temperatures • Summer temperatures may be high
Mediterranean (Csa, Csb) • Distinct summer dry period • Subtropical high interactions • Winter precipitation is variable • Mild winter temperatures • Mild to hot summers
Humid Subtropical (Cfa, Cwa) • Eastern continental areas of the lower mid-latitudes • High heat and moisture • Abundant and even monthly precipitation • Weather influenced by subtropical highs • Mild winters • Hot summers
Marine West Coast (Cfb, Cfc) • Poleward of Csb • Cold ocean current influence • Often has fog and/or low cloud cover • Mild and even annual temperatures • High frequency of rain days
Severe Mid-latitude Climate • Very cold winters • Large continental areas • Evenly distributed annual precipitation • Humid Continental (Dfa, Dfb, Dwa, Dwb) • Eastern continents - 40o-55o N • Warm to hot summers • Cold winters • Even and abundant annual precipitation
Subarctic (Dfc, Dfd, Dwc, Dwd) • Poleward of humid continental climates • Coniferous boreal forest (taiga) • Warm, short summers • Low annual precipitation (summer maximum)
Polar Climates • Very high latitudes • Very cold • Tundra (ET) • Tundra vegetation • Harsh winters • Mild summers of long days • Permafrost region
Ice Cap (EF) • Constant ice cover • Greenland and Antarctica • Warmest monthly temperatures < 0oC • Katabatic winds • Low precipitation
Highland Climates (H) • Governed solely by topography • Vertical zonation • Highly variable local climates
End of Chapter 15Understanding Weather and Climate4th EditionEdward Aguado and James E. Burt