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Chapter 10: Middle-Latitude, Polar, and Highland Climate Regions

Physical Physical GeographyGeographyNinth EditionNinth Edition

Robert E. Gabler

James. F. Petersen

L. Michael Trapasso

Dorothy Sack

Middle-Latitude, Polar, and Highland Climate Regions

Forests surround a small glacier in Alaska

10.1 Middle-Latitude Climates

• Microthermal and Mesothermal: – A lot of change and most of

the World’s population!– Changing seasons

associated with:• Migrating air masses• Cyclonic activity along polar

front.

10.1 Middle-Latitude Climates

• Humid Mesothermal Climate Regions– Moderate temperate (mesos)– Seasonality (long summers and short winters)

10.1 Middle-Latitude Climates

• Mesothermal Climates

10.1 Middle-Latitude Climates

• Mediterranean (Csa, Csb)– Location: west coasts 30o-

40o latitude– Alternation of subtropical

High in summer (dry) and westerlies in winter (wet)

– Csb has lower summer temp. (strong maritime)

– Csa has hot summers (continentality)

10.1 Middle-Latitude Climates

• Mediterranean– Special Adaptations– Chaparral

Q: Why is it unusual to find redwoods growing in this climate?

10.1 Middle-Latitude Climates

• Humid Subtropical Climate (Cfa)– Location: east coasts 15o and

20o to 40o latitude– Warm, moist air circulates

from the south around subtropical High in summer (wet and hot)

– Westerlies in winter (wet and cool)

10.1 Middle-Latitude Climates

• Humid Subtropical Climate (Cfa)– Subject to Tropical Storms,

convectional activity, and/or monsoon

– Wetter than Mediterranean even though similar latitude.

10.1 Middle-Latitude Climates

• Humid Subtropical Climate (Cfa)– Productive Climate– Long growing season

10.1 Middle-Latitude Climates

• Marine West Coast (Cfb and Cfc)– Location: 40o and 65o

latitude.– Continuous influence of

westerlies– Ample precipitation

• Mild-summer (Cfb)• Cool-summer (cfc)

10.1 Middle-Latitude Climates

• Ocean Influences– Moderating influences on temperature– Ocean current may increase– Smaller diurnal and annual temperature range

Q: How do you explain these differences?

10.1 Middle-Latitude Climates

• Clouds and Precipitation– Very cloudy, foggy

(advection fog), rainy, and stormy (cyclonic storms)

– Mountains increase precip. on windward side

– Heavy snow

10.1 Middle-Latitude Climates

• Resource Potential– Advantages for

agriculture– Small annual temp

range, long growing season, and abundant precip. favor plant growth

– Root crops, deciduous fruits, berries, grapes, grass, and timber

10.2 Humid Microthermal Climate Regions

• Humid Microthermal (35o-75oN)– Variable– Four distinct seasons– Continentality

10.2 Humid Microthermal Climate Regions

• Humid Microthermal– Humid continental, hot summer (Dfa, Dwa)– Humid continental, mild summer (Dfb, Dwb)– Subarctic with a cool summer (Dfc, Dfd, Dwc,

Dwd)– Similarities:

• All of these experience surplus of precip over potential ET

• Year round precip. (except area in Asia)• High frequency of mT in summer and cP in winter• Cyclonic storms and polar jet

10.2 Humid Microthermal Climate Regions

• Humid Microthermal

10.2 Humid Microthermal Climate Regions

• What areas of the U.S. average the greatest number of days of snow cover?

10.2 Humid Microthermal Climate Regions

• Humid Continental, Hot Summer (Dfa, Dwa)– Large geographic distribution in North America,

much smaller in Europe and Asia– Greatest agriculture potential– Longer growing season– Lower fuel bills

• Internal Variations of Dfa, Dwa– Growing season (140-200 days) depends on lat.– Continentality– Large lakes– Temp and precip decrease poleward

10.2 Humid Microthermal Climate Regions

• Internal Variations of Dfa, Dwa– Precipitation decrease

away from sea water.

Q: Why does precipitation decrease inland and poleward?

10.2 Humid Microthermal Climate Regions

• Seasonal Changes– Winter (cold and snowy)– Spring (warmer with frequent showers)– Summer (Hot and humid with occasional violent

thunderstorms)– Fall (clear and rainy, mild days, and frosty

nights)

10.2 Humid Microthermal Climate Regions

10.2 Humid Microthermal Climate Regions

• Humid Continental, Mild Summer (Dfb, Dwb)– Lies adjacent to and poleward of Dfa and Dwa– More continental with severe winters– Highly variable weather– Many cyclonic storms along polar front

• Mild-Summer & Hot-Summer ComparisonQ: What characteristics of these climographs distinguish

them from Galesburg, IL. & Northeast China

10.2 Humid Microthermal Climate Regions

10.2 Humid Microthermal Climate Regions

• Mild-Summer & Hot-Summer Comparison– More severe winters– Shorter growing season– Less precipitation, but

more snowfall

10.2 Humid Microthermal Climate Regions

• Human Activity– Dairy farming, quick ripening

varieties, grazing, animals, or orchards

– Poorer soil due to glacial impact during Pleistocene

– Many recreational activities

10.2 Humid Microthermal Climate Regions

• Subarctic (Dfc, Dfd, Dwc, Dwd)– At least one month with an average temperature

above 10oC (50oF)– Farthest poleward of microthermal climates

10.2 Humid Microthermal Climate Regions

• Subarctic (Dfc, Dfd, Dwc, Dwd)– Found only in N. hem– Ocean Currents

• East Coast: subarctic is further south• West: subarctic is further north

– Subarctic covers vast areas of Eurasia and North America

10.2 Humid Microthermal Climate Regions

• Subarctic (Dfc, Dfd, Dwc, Dwd)– Short cool summers and long harsh winters

Q: Why would people settle in such severe-winter climate regions?

10.2 Humid Microthermal Climate Regions

• Limiting Environment– Plants and animals– Taiga (boreal forest)– Very short growing season

(50-75 days)

10.2 Humid Microthermal Climate Regions

• Limiting Environment– Permafrost: permanently

frozen ground– Permafrost varies greatly

in thickness and is often discontinuous

– Freeze/thaw cycle– Patterned ground (frost

polygons)– Little to no agriculture– Mining

10.3 Polar Climate Regions

• Polar Climates (furthest from equator)– No month averages above 10oC (50oF)– No summer– No trees– Large annual net loss of radiation– Two Climate types:

• ET (Tundra)• EF (ice sheet)

10.3 Polar Climate Regions

• Polar Climates (ET and EF)

• Tundra Climate (ET)– Extremely short, cool “summer”– Muskeg

10.3 Polar Climate Regions

• Tundra Climate (ET)Q: What is the preferred means of travel in the

summer?

10.3 Polar Climate Regions

• Ice-Sheet Climate (EF)– Covers large areas on Northern and Southern

hemispheres (Greenland and Antarctica)

10.3 Polar Climate Regions

• Ice-Sheet Climate (EF)– Coldest place on earth is Antarctica (minimum

insolation, high albedo, and high elevation)

10.3 Polar Climate Regions

• Human Activity in Polar Regions– Inuit– Oil (Alaska’s North

Slope)– Scientific interest

10.3 Polar Climate Regions

• Highland Climate– Temperature decreases

with increasing altitude– Exposure

• Coastal or interior location

• High or low latitude• Slope aspect

10.3 Polar Climate Regions

Q: Taking into consideration the location of the stations, during what season does the maximum precipitation on the windward slope occur?

10.3 Polar Climate Regions

• Peculiarities of Mountain Climates– Tree line– Snow line

Q: What do you see in the photo that indicates prevailing wind direction?

10.3 Polar Climate Regions

• Peculiarities of Mountain Climates– Tropical Mountain

regions

Q: When Europeans first settled in the highlands of tropical S. America, in which vertical climate zone did they prefer to live in?

10.3 Polar Climate Regions

• Highland Climates and Human Activity– High pastures– Timber– Minerals– Recreation– With warming, tropical

highlands may become new areas of settlement

10.3 Polar Climate Regions

Physical Geography

End of Chapter 10: Middle-Latitude, Polar, and Highland Climate Regions