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Title Page Photo

““I've lived in good climate, and it bores the hell I've lived in good climate, and it bores the hell out of me. I like weather rather than climate.”out of me. I like weather rather than climate.”

——John Steinbeck (Brainquote.com)John Steinbeck (Brainquote.com)

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Climate Classification• The Purpose of Classifying Climates

– To understand distribution of climates– To compare climates of different places

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• The Early Greek Classification Schemes– Greeks

• Temperature and latitude

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– Major climate zones of the Old World, as recognized today1) Equatorial warm wet2) Tropical hot dry3) Subtropical warm temperate4) Midlatitude cool temperate5) High-latitude cold

– Fig. 8-2

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The Köppen Classification System• Empirical System

– Has a numerical basis• Temperature data• Precipitation data

• Teaching tool– Simple to comprehend and to use– Shows an orderly pattern over the world– Gives some indication of climate origin (genesis)

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• Modified Köppen System– Five major climate groups

• Groups A, B, C, D, and E– 14 individual climate types

• Special category of highland (H) climate

– Fig. 8-3

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– Climatic Regions of the World

• Fig. 8-4

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Tropical Humid Climates (Group A)• Distribution of A Climates

– Within 0–25º of equator

• Fig. 8-6

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• Fig. 8-8

• Distinctive Features of A Climates– Average daily temperature greater than annual

temperature range

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– No true winter• “Winter” in tropics refers to the “low-sun” half of the year

“Summer” refers to the “high-sun” half of the year

– High temperatures prevail every month• A climates are distinguished by the monthly pattern of

rainfall– f = year-around rainfall– m = year-round rainfall, but with a brief drier period– w = wet summer and dry winter

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Tropical Wet Climate (Af)• Main locations

– Within 5–10º of equator – Amazon basin– Northern Congo basin– Islands of East Indies

• Characteristics─ Monotonous (“seasonless”)

“Night is the season of the tropics”─ High humidity─ Afternoon convective thundershowers─ High annual rainfall, evenly distributed during year

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• Dominant Controls– ITCZ influence entire year

• Animated Drawing (toggle forward-back-forward)

Convectiveprecipitation

30ºN30ºS

0º 10ºS10ºN

cTNH summerwet season

TradesTrades

SH winterdry season

cT

NH winterdry season

Trades Trades

SH summerWet season

Af

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• Climographs

– Fig. 8-7

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• Main locations– 5–25º of latitude– Most extensive of A climates – Adjacent to Af climates– Most widespread in Africa, South America– South Asia and northern Southeast Asia– Northern Australia• Characteristics

• Clear-cut seasonal alternation of wet and dry periods• Lower precipitation than other A climates

Tropical Savanna (AW)

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• Dominant Controls– ITCZ dominates during summer – cT or cP air mass dominates during winter

• Fig. 8-11

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• Climographs

– Fig. 8-10

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Tropical Monsoon (AM)• Main locations

– Coastal regions– Most prominent area is west-facing coasts of

India, southeastern Asia– Smaller areas scattered in tropical latitudes

• Characteristics– Very high rainfall totals in summer– Brief (1-4 months), drier period in winter

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• Dominant Controls– ITCZ movement– Jet Stream fluctuation– Continental pressure changes

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• Climographs

– Fig. 8-12

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Dry Climates (Group B)– Fig. 8-14

• Distribution of B Climates– Subtropical Dry Climates within 20–35º of latitude– Midlatitude Dry Climates within 35-55º of latitude

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• Distinctive Features of B climates– Cover 30% of the total land area of the world

• More area than any other climate group

– Dry conditions prevail all year• Potential evapotranspiration is greater than precipitation

– Two main sub-types based on precipitation• BW is extremely arid (desert)• BS is steppe (semi-arid)

– The two sub-types are further subdivided based on temperature• h is for the hot subtropical desert (BWh, BSh)• k is for the cold midlatitude desert (BWk, BSk)

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Subtropical Desert (BWh)• Main locations

– Centered at latitudes 25–30º– Western sides of continents,

including coasts• Extend into continental interiors

– Northern Hemisphere• Sonora-Colorado• Sahara• Arabian

– Southern Hemisphere• Peru-Atacama• Kalahari-Namib

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• Characteristics– Precipitation: extremely arid

• Scarce (most nearly rainless regions on Earth)• Unreliable (extremely long periods without rain)• Intense (brief, but heavy convective downpours)

– Very hot summers– Enormous daily temperature range– Coastal equatorward extensions: advection fog

off-shore

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• Dominant Controls– Subsidence from subtropical highs (STHs)

• Fig. 8-15

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– Cold ocean currents• Equatorward extensions

– Fig. 8-17

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• Cool, foggy west coast deserts

– Fig. 8-18

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• Climographs

– Fig. 8-16

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Subtropical Steppe (BSh)• Main locations

– Fringing BWh except on west coasts

• Characteristics– Similar to BWh but more moderate– Precipitation: semiarid

• Dominant Controls• Similar to BWh

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• Climographs

– Fig. 8-20

(Richard A. Crooker photos)

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Midlatitude Desert (BWk)• Main locations

– Central Asia– Western interior

of United States– Patagonia

– Fig. 8-14

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• Characteristics– Precipitation meager

• Erratic, mostly showery• Some winter snow

– Temperatures• Hot summers, cold winters• Very large annual temperature range• Large daily temperature range

• Dominant Controls– Rain shadow effects– Distance from sources of moisture

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• Climographs

– Fig. 8-21

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Midlatitude Steppe (BSk)• Main locations

– Fringing BWk

• Characteristics– Similar to BWk

(more moderate)– Precipitation:

semiarid

• Dominant Controls– Similar to BWk

– Fig. 8-14

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• Climographs

– Fig. 8-22

Photograph Source: U.S. Geological Surveyhttp://www.usgs.gov/125/articles/conservation.html

Photo: U.S. Great Plains, South Dakota

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Mild Midlatitude Climates (Group C)– Fig. 8-23

• Distribution of C Climates– Equatorward margin of the middle latitudes– Within 25-40º of latitude with some poleward

extensions

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• Distinctive Features of C climates– Temperatures

• Long summers, usually hot• Short winters, relatively mild

– Precipitation• No year-round moisture deficiency• Some climates have seasonal shortages

– Three subtypes• Mediterranean (Csa, Csb)• Humid subtropical (Cfa)• Marine west coast (Cfb, Cfc)

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Mediterranean Climates (Csa, Csb)• Main locations

– Western side of continents• 30–40º of latitude

– Mediterranean coast– California– Central Chile– Southern tip of Africa (Cape Town)– Australia (Perth & Adelaide)

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• Characteristics– Mild, wet winters, dry summers– Two sub-types based on summer temperatures

• a – hot summer (interior location)• b – cool/mild summer (coastal location)

• Fig. 8-26

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• Dominant Controls– STH subsidence in summer (forces cyclonic

storms poleward)– Westerly winds and cyclonic storms shift

equatorward in winter

– Precipitation• Moderate annually• Winter maximum (midlatitude cyclonic storms)

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• Climographs

– Fig. 8-24

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Humid Subtropical (Cfa, Cwa)• Main locations

– Eastern sides of continents• 25–30º of latitude

– Southeastern United States– Eastern China– Southern Brazil and Uruguay– Small areas in Africa and Australia

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• Characteristics– Temperatures

• Summers, warm to hot• Winters, mild to cold

– Precipitation• Abundant, mostly as rain• Summer maximum

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• Climographs

– Fig. 8-27

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Marine West Coast• Main locations

– Western sides of continents, mainly• 40–65º

– Western and central Europe• Largest area

– North America• Oregon to Alaska

– New Zealand and eastern Australia

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• Characteristics– Temperature

• Very mild winters for latitude

– Precipitation• Moderate to abundant, mostly in winter• Many rainy days• Much cloudiness

• Dominant Controls– Westerly flow and oceanic influence year-round

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• Climographs

– Fig. 8-30

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Severe Midlatitude Climates (Group D)– Fig. 8-31

• Distribution of D Climates– Only in Northern Hemisphere– Within 35–70º of latitude

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• Distinctive Features of D climates– Temperatures

• Large annual temperature range– Continentality

• Cold winter, relatively short summer

– Precipitation• Summer maxima• Abundant to meager amounts• Diminishes toward inland and poleward

– Two Main Subtypes• Humid Continental• Subarctic

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Humid Continental (Dfa, Dfb, Dwa, Dwb)• Location

– N. Hemisphere only– 35–55º of latitude– Eastern sides of continents

– Fig. 8-31

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• Characteristics– Temperature

• Warm/hot summers• Large annual temperature range

– Precipitation• Moderate to abundant• Summer maxima

• Dominant Controls– Westerly winds and storms

• Midlatitude cyclones in winter in North America• Monsoons in Asia

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• Climographs

– Fig. 8-32

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Sub Arctic (Dfc, Dfd, Dwc, Dwd)

• Location– Northern Hemisphere only– Latitudes 50–70º– Across North American and Eurasia

• Characteristics– Temperature

• Long, dark, very cold winters• Brief, mild summers• Enormous annual temperature range

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– Precipitation• Meager• Summer maxima• Light snow in winter, little melting

• Dominant Controls– Pronounced continentality– Alternating…

• Westerlies and cyclonic storms• Prominent anticylcones

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• Climographs

– Fig. 8-35

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Polar Climates (Group E)

• Distribution of E Climates– Poleward of 70º of latitude

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• Distinctive Characteristics– Temperatures

• Coldest summers• Lowest annual average• Large annual temperature range• Small daily temperature range

– Extraordinarily dry• Low precipitating, mostly snow• Evaporation is nil

– Two subtypes• Tundra• Ice Cap

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Tundra (ET)• Main Locations

– Fringes of Arctic Ocean– Small coastal areas in Antarctica

• Fig. 8-36

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• Characteristics– Temperature

• Long, cold dark winters• Brief, cool summers

– Precipitation• Very sparse• Mostly snow

• Dominant Controls– Latitude– Distance from sources of heat and moisture– Extreme seasonal contrasts in sunlight/darkness– Polar anticyclones (A and cP air masses)

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• Climographs

– Fig. 8-37

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Ice Cape (EF)• Location

– Antarctica– Greenland

• Characteristics– Temperature

• Long, cold, dark winters

• Cold, windy summers

– Precipitation• Very sparse, all

snow

• Fig. 8-36

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• Dominant Controls– Latitude– Distances from sources of heat and moisture– Extreme seasonal contrasts in sunlight/darkness– Polar anticyclones (A and cP air masses)

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• Climographs

– Fig. 8-38

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Highland Climate (Group H)• Locations

– High uplands (mountains and plateaus)

– Fig. 8-40

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• Characteristics– Complex local variation in small areas– Vertical climate zonation

– Fig. 8-42

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– Changeability of weather– Fig. 8-43

• Dominant Controls– Altitude– Slope aspect and slope angle

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• Climographs

– Fig. 8-41

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Global Patterns Idealized• General Models of the Climate Distribution

– Idealized seasonal precipitation patterns and climates along the west coasts of continents (Fig. 8-44).

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– Idealized Global Pattern

– Fig. 8-45

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• Climatic Distribution in Africa: A Practically Perfect Example

– Fig. 8-45 and Fig. 8-46

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• The modified Köppen system recognizes six major climatic zones:1. Tropical humid (A)2. Dry (B)3. Mild midlatitude (C)4. Severe midlatitude (D)5. Polar (E)6. Highland (H)

• A model of climate distribution on a hypothetical continent helps use predict what the climate should be like at a particular location.