Chapter 15 Lecture Understanding Weather and Climate Seventh Edition Earth’s Climates Frode Stordal, University of Oslo Redina L. Herman Western Illinois University © 2015 Pearson Education, Inc. 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. © 2015 Pearson Education, Inc. The Köppen System • The Köppen climate classification system is based on natural vegetation types as indicators of average temperature and precipitation. © 2015 Pearson Education, Inc. 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. © 2015 Pearson Education, Inc. The Köppen System © 2015 Pearson Education, Inc. The Köppen System © 2015 Pearson Education, Inc. The Köppen System © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. 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 © 2015 Pearson Education,wet Inc. climates on the other. Tropical Climates • Tropical Wet (Af) © 2015 Pearson Education, Inc. Tropical Climates • Monsoonal (Am) © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. 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. © 2015 Pearson Education, Inc. Dry Climates • Subtropical Deserts (BWh) © 2015 Pearson Education, Inc. Dry Climates • Subtropical Steppe (BSh) © 2015 Pearson Education, Inc. Dry Climates • Midlatitude Deserts (BWk) © 2015 Pearson Education, Inc. Dry Climates • Midlatitude Steppe (BSk) © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. 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. © 2015 Pearson Education,– Often Inc. has fog and/or rain, with low annual totals. Mild Midlatitude Climates • Mediterranean (Csa, Csb) © 2015 Pearson Education, Inc. Mild Midlatitude Climates • Humid Subtropical (Cfa, Cwa) © 2015 Pearson Education, Inc. Mild Midlatitude Climates • Marine West Coast (Cfb, Cfc) © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. 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. © 2015 Pearson Education, Inc. Severe Midlatitude Climates • Humid Continental (Dfa, Dfb, Dwa, Dwb) © 2015 Pearson Education, Inc. Severe Midlatitude Climates • Subarctic (Dfc, Dfd, Dwc, Dwd) © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. 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. © 2015 Pearson Education, Inc. Polar Climates • Tundra (ET) © 2015 Pearson Education, Inc. Polar Climates • Ice Cap (EF) © 2015 Pearson Education, Inc. The Köppen System (rev) Peel et al., 2007 © 2015 Pearson Education, Inc. The Köppen System (rev) Peel et al., 2007 © 2015 Pearson Education, Inc. .