Chapter 13: Global Climate By the end of this chapter you should: By the end of this chapter you should: Understand the controls of climate Understand

Chapter 13: Chapter 13: Global ClimateGlobal Climate

By the end of this chapter youBy the end of this chapter youshould:should:

Understand the controls of climateUnderstand the controls of climate

Have an understanding of the Köppen system Have an understanding of the Köppen system

Global TemperaturesGlobal Temperatures

Controls on climate:Controls on climate:- intensity of sunshine and its variation - intensity of sunshine and its variation with latitudewith latitude

- distribution of land and water- distribution of land and water- ocean currents- ocean currents- prevailing winds- prevailing winds

- location of high and low pressure areas- location of high and low pressure areas- mountain barriers- mountain barriers- altitude- altitude

Fig. 13-1, p. 355

Global TemperaturesGlobal Temperatures ““Bending” of isotherms near the continentsBending” of isotherms near the continents

Isotherms are west to east (solar radiation)Isotherms are west to east (solar radiation) Coldest temperatures over the interior of Coldest temperatures over the interior of continents, warmest in subtropical desertscontinents, warmest in subtropical deserts

Global PrecipitationGlobal Precipitation Where air is rising, expect rain. Sinking air, expect a dry Where air is rising, expect rain. Sinking air, expect a dry

climateclimateITCZ produces a tremendous amount of rainITCZ produces a tremendous amount of rain

Influence of orographic uplift and rain shadowsInfluence of orographic uplift and rain shadows

Fig. 13-2, p. 356

Climatic Classification - Climatic Classification - the Köppen Systemthe Köppen System

Tropical moist climates - average temp. Always above Tropical moist climates - average temp. Always above 64°F. Basically no winter64°F. Basically no winter

Dry climates – Evaporation and transpiration greater Dry climates – Evaporation and transpiration greater than precipitationthan precipitation Moist mid-latitude climates with mild winters – warm-to-hot Moist mid-latitude climates with mild winters – warm-to-hot summers, mild winters. Ave. temps. coldest month between summers, mild winters. Ave. temps. coldest month between 64°F and 27°F64°F and 27°F Moist mid-latitude climates with severe winters – warm Moist mid-latitude climates with severe winters – warm summers and cold winters. Ave. temps warmest month summers and cold winters. Ave. temps warmest month between 50°F and 27°Fbetween 50°F and 27°F Polar climates – Extremely cold winters and summers. Ave Polar climates – Extremely cold winters and summers. Ave temp between 50°F in warmest month. No summer.temp between 50°F in warmest month. No summer.

Climatic Classification - Climatic Classification - the Köppen Systemthe Köppen System

Criticized because:Criticized because: Boundaries do not relate to natural boundaries in Boundaries do not relate to natural boundaries in

climatic zonesclimatic zones System implies sharp changes. In reality, they are System implies sharp changes. In reality, they are

more subtlemore subtle

Fig. 13-6, p. 361

The Global Pattern of The Global Pattern of ClimateClimate

Tropical Moist Climates Tropical Moist Climates (Group A)(Group A)

Tropical wet (Af)Tropical wet (Af) Warm all seasonsWarm all seasons Lots of rainLots of rain N and S of equatorN and S of equatorto 15° to 25°to 15° to 25° Rainfall greaterRainfall greaterthan 59 in.than 59 in.



Tropical monsoon (Am)Tropical monsoon (Am) Precip drops below 6 cm for one or two monthsPrecip drops below 6 cm for one or two months Annual precipitation amounts are similar to AfAnnual precipitation amounts are similar to Af


Tropical wet and dry (Aw)Tropical wet and dry (Aw) Distinct dry seasonDistinct dry season Jungle can not surviveJungle can not survive

Savanna grassSavanna grass

Dry Climates (Group B)Dry Climates (Group B) Arid (Bw)Arid (Bw)

Deficient precipitationDeficient precipitation Sonoran and Mojave deserts (Rain shadow)Sonoran and Mojave deserts (Rain shadow)

Dry Climates (Group B)Dry Climates (Group B) Semiarid (BS)Semiarid (BS)

Transition between aridTransition between arid

and more humid climatesand more humid climates

Moist Subtropical Mid-Moist Subtropical Mid-latitude Climates (Group latitude Climates (Group

C)C) Humid subtropical (CfA)Humid subtropical (CfA)

Humid and mild wintersHumid and mild winters Eastern and westernEastern and westernregions of most continentsregions of most continents

Hot, muggy summersHot, muggy summers Mild wintersMild winters

Snowfall is rareSnowfall is rare


C)C) Marine (CfB)Marine (CfB) Summers are coolSummers are cool Long summersLong summers

Mountains thatMountains thatparallel coast haveparallel coast haveeffecteffect

Clouds and drizzleClouds and drizzle


C)C) Mediterranean (Cs)Mediterranean (Cs)

Dry summers, influenced by the subtropical highsDry summers, influenced by the subtropical highs

Moist Continental Moist Continental Climates (Group D)Climates (Group D)

Warm to cool summers, cold wintersWarm to cool summers, cold winters Winters are severe (cold, snowstorms)Winters are severe (cold, snowstorms) Controlled by large landmasses (N.H.)Controlled by large landmasses (N.H.) Coldest month average below 27°FColdest month average below 27°F Can still have treesCan still have trees


Humid continental with hot summers (Dfa) Latitude 40°N to 50°N Precipitation between 20 and 40 in. Hot summers (exceed 90°F)


Humid continental with cool summers (Dfb)Humid continental with cool summers (Dfb)

Cooler and less Cooler and less humid than Dfahumid than Dfa

Hot spells shorterHot spells shorter Winters long, cold Winters long, cold

windywindy Large temperature Large temperature

range like Dfarange like Dfa


Subpolar (Dfc) Severe winters, short summersSevere winters, short summers Only 1 month w/ mean temp > 50°FOnly 1 month w/ mean temp > 50°F Large temperature rangesLarge temperature ranges Precipitation is lightPrecipitation is light Boreal climateBoreal climate

Polar Climates (Group E)Polar Climates (Group E) Always low temperatures One type has at least one month above freezing…one

doesn’t

Polar Climates (Group E)Polar Climates (Group E) Polar tundra (ET)Polar tundra (ET)

Always low temperatures (warmest month < 50°FAlways low temperatures (warmest month < 50°F Permafrost is abundant/Low precipitation amountsPermafrost is abundant/Low precipitation amounts Tundra vegetation (mosses, scattered wooded areasTundra vegetation (mosses, scattered wooded areas Large temperature rangesLarge temperature ranges

Polar Climates (Group E)Polar Climates (Group E)

Polar ice caps (EF)Polar ice caps (EF) Average temp always Average temp always

below freezingbelow freezing No plantsNo plants Covered in snow and Covered in snow and

iceice Little precipitationLittle precipitation Katabatic winds Katabatic winds

presentpresent

Highland Climates Highland Climates (Group H)(Group H)

Altitude effects are similar to latitude effectsAltitude effects are similar to latitude effects

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Chapter 13: Global Climate By the end of this chapter you should: By the end of this chapter you should: Understand the controls of climate Understand