Chapter 15 Lecture Understanding Weather and Climate Seventh Edition Earth s Climates Frode Stordal, University of Oslo Redina L. Herman Western Illinois University
Climate and Controlling Factors Climate is the long-term statistical properties of the atmosphere for an area. Climate analysis for an area includes many variables. Climate classifications are based on properties such as temperature, precipitation, air mass types, and seasonal variations in water balance for an area.
The Köppen System The Köppen climate classification system is based on natural vegetation types as indicators of average temperature and precipitation.
The Köppen System A Tropical. Climates in which the average temperature for all months is greater than 18 C. Almost entirely confined to the region between the equator and the tropics of Cancer and Capricorn. B Dry. Potential evaporation exceeds precipitation. C Mild Midlatitude. The coldest month of the year has an average temperature higher than 3 C (or 0 C) but below 18 C. Summers can be hot. D Severe Midlatitude. Winters have at least occasional snow cover, with the coldest month having a mean temperature below 3 C (or 0 C). Summers are typically mild. E Polar. All months have mean temperatures below 10 C.
The Köppen System
The Köppen System
The Köppen System
Tropical Climates Tropical Climates Warm annual temperatures and little temperature variation. Distinguished by precipitation variations. Tropical Wet (Af) Even precipitation through year, high humidity Monsoonal (Am) Transition climate between tropical wet and tropical wet dry Precipitation does not occur steadily throughout the year The wet months yield far more rain than does the wettest month for tropical wet climates. Tropical Wet and Dry (Aw) Tropical wet and dry climates occur along the poleward sides of the tropics and border dry climates on one side and tropical wet climates on the other.
Tropical Climates Tropical Wet (Af)
Tropical Climates Monsoonal (Am)
Dry Climates Dry climates occur in areas where potential evapotranspiration is greater than precipitation. 30% of Earth s land surface is classified as a dry climate. Semideserts/steppe are transitional zones that separate the true deserts from adjacent climates. The two-tiered system of categorization yields four types of dry climates: subtropical desert, subtropical steppe, midlatitude desert, and midlatitude steppe.
Dry Climates Subtropical Deserts (BWh)
Dry Climates Subtropical Steppe (BSh)
Dry Climates Midlatitude Deserts (BWk)
Dry Climates Midlatitude Steppe (BSk)
Mild Midlatitude Climates Mild midlatitude climates located in parts of the latitude range 30-60 Varying precipitation systems with mild winter temperatures. Summer temperatures may be high. Mediterranean (Csa, Csb) Mild to hot and dry summers. Winter precipitation varies while temperatures are mild. Humid Subtropical (Cfa, Cwa) Long, hot, and muggy summers. Winter temperatures are lower than those of mediterranean climates. Marine West Coast (Cfb, Cfc) Cold ocean current influence with mild summers and winters. Often has fog and/or rain, with low annual totals.
Mild Midlatitude Climates Mediterranean (Csa, Csb)
Mild Midlatitude Climates Humid Subtropical (Cfa, Cwa)
Mild Midlatitude Climates Marine West Coast (Cfb, Cfc)
Severe Midlatitude Climates Severe Midlatitude Climates Very cold winters. Large continental areas. Evenly distributed annual precipitation. Humid Continental (Dfa, Dfb, Dwa, Dwb) Eastern continents of 40 N 55 N. Warm to hot summers and cold winters. Abundant annual precipitation. Subarctic (Dfc, Dfd, Dwc, Dwd) Contains the coniferous boreal forest (taiga Asia). Warm, short summers and extremely cold winters. Low annual precipitation with the moistest season being summer.
Severe Midlatitude Climates Humid Continental (Dfa, Dfb, Dwa, Dwb)
Severe Midlatitude Climates Subarctic (Dfc, Dfd, Dwc, Dwd)
Polar Climates Polar climates Very cold. Tundra (ET) Named for vegetation (tundra). Severe winters, mild summers of long daylight. Permafrost (permanently frozen layer below the surface) Ice Cap (EF) Constant ice cover, Greenland and Antarctica. Warmest monthly temperatures are less than 0 C. Low precipitation totals. Highland Climates (H) Governed solely by topography and not geographic location. Vertical zonation, as climate changes with height (mountainous regions). Local climates contain high variability.
Polar Climates Tundra (ET)
Polar Climates Ice Cap (EF)
The Köppen System (rev) Peel et al., 2007
The Köppen System (rev) Peel et al., 2007