Class #32: Friday, November 131 Class #33: Monday, November 16 Climate types (continued)

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Class #33: Monday, November 16

Climate types (continued)

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Köppen (KEPP-in) Scheme

• Modified by Trewartha and Horn

• Related to geography and global circulation

• Uses letters (1, 2 or 3) in Chapter 14

• Has many other subdivisions within the categories shown in our book

• Has 6 major groups: A, B, C, D, E, H

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The 6 major climate groups

• A: Tropical moist• B: Dry (can be subtropical or mid latitude)• C: Moist with mild winters (mid latitude)• D: Moist with severe winters (mid latitude)• E: Polar (high latitude)• H: Highland (rapid climate change with

elevation)• 2nd letter: usually latitude (except B)• 3rd letter: differences in temperature

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Tropical Humid Climates: Af, Aw, Am

• All tropical (A) climates are humid

• Letter “f” means no dry season, rain year round, usually closest to the equator

• Letter “m” means “monsoonal”, with a short dry season and a very rainy season

• Letter “w” means “winter dry season” except no real winter in tropics, just cool

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Tropical humid climates (continued)

• Af – Closest to the equator– Smallest annual range of temperature– 6.9-10 inches of rain per month– Most thunderstorms in afternoon– Linked to ITCZ– Tropical rain forests

• Am– Seasonal onshore winds during summer monsoon– Climates with most yearly precipitation– Jungle vegetation

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Tropical moist climates (continued)

• Aw– Farthest A climate from the equator– Often border Af– Tropical wet and dry– Wet summers, dry, cooler winters– Linked to the seasonal migration of the ITCZ– Vegetation is savannah or tropical grasslands with

scattered deciduous trees, as in the grasslands of Africa.

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Dry (B) climates

• Potential evaporation minus precipitation is greater than 0

• More land of this climate type than any other

• Lubbock has a B climate

• Descending branch of the Hadley circulation near the subtropical highs or

• Rain shadow of a mountain range

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Dry climate subtypes

• 2nd letter– “S” for steppe or semi-arid (like Lubbock)– “W” for true desert (extremely dry)

• 3rd letter– “h” for low-latitude, hot (yearly average

temperature >= 64ºF)– “k” for mid latitude, cool (yearly average

temperature <64ºF)

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Dry climate subtypes (continued)

• BWh Extremely dry and hot; can have large sand dunes; Sahara, Arabian peninsula, central Australia, most extreme B climate

• BSk Least extreme B climate; midlatitude steppe, often high plateau, Lubbock, Denver, San Diego; often rain shadow

• BSh Much of Mexico, lower latitude, subtropical steppe

• BWk Central Asia, very dry, midlatitude rain shadow, continental interior

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C Climate type

• All C are moist, plentiful precipitation• All C are midlatitudes• Average temperature of coolest month between

27ºF and 65ºF• Have many subtypes; Chapter 14 concentrates

on a few• 2nd letter like A subtypes

– “f” no dry season– “w” brief dry period in winter

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C Climate type (continued)

• 3rd letter– “a” hot summer– “b” warm summer– “c” cool summer

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C Climate subtypes

• Cfb, Cfc Marine west coast– Northwest coast of US, Canada– Often cool ocean currents

• Cfa, Cwa Humid subtropical– Southeastern US– 30-100 inches of rain per year

• Csa, Csb Mediterranean– Along a coast, mild winter– Greece– Dry summer, semi-permanent subtropical high

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D Climate typeSevere (winter) Midlatitude

• Similar to C but severely cold winter

• Average temperature of coldest month <27ºF

• Snow on ground for extended periods

• Average temperature of warmest month >50ºF

• Overall, large change in temperature with season

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D climate subtypes

• 2nd letter – “f” no dry season– “w” winter dry season

• 3rd letter– “a” hot summer– “b” warm summer– “c” cool summer– “d” extremely severe winter

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D Climate Subtypes (continued)

• Humid continental– Dfa, Dfb, Dwa, Dwb– Dfa, for example, Chicago

• Subarctic– Dfc, Dfd, Dwc, Dwd– Long winter– Brief cool summer

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E climate type

• Polar climate, very dry and cold

• Poleward of Arctic/Antarctic Circle, latitude 66.5º

• E climate subtypes– ET Tundra: mosses, lichens, flowering plants,

woody shrubs, small trees, permafrost– EF Ice caps: no vegetation; Greenland,

Antarctic Plateau

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Class #32: Friday, November 13 29

H climate type: Highland

• Large variation of temperature and precipitation over small horizontal distances

• Large diurnal temperature variation

• Can be dry or moist, depending on orientation, humidity, and whether prevailing winds are upslope or downslope