Chapter 9Water Resources

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen

Chapter 9You are responsible for pages 245-248 in chapter 9

WaterConstantly cycling through the environmentWater spends time in the ocean, the air, on the surface, and underground.Hydrologic Cycle: the circulation and transformation of water through Earth’s atmosphere, hydrosphere, lithosphere, and biosphere.Water-resource management:

Wells, reservoirs, dams

Water Budget

97% of Earth’s water in the ocean, so most precipitation and evaporation takes place thereThe bulk of global precipitation comes from ocean water

86% of all evaporation traced to ocean

14% of all evaporation traced to the land

TranspirationThe movement of water vapor through the pores of leaves and into plants through roots from soil moisture.

Evaporation

The movement of free water molecules away from a wet surface into the air that is less saturated.

Water spends 10 days (on average) in the atmosphere

Water spends 3,000-10,000 years in deep-ocean circulation, groundwater aquifers, glacial ice

End of Chapter 9

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen

Chapter 10Global Climate Systems

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen

ClimateClimate is weather averaged over time over broader geographic areas.Usually averaged over 30-yr periods.Climatology is the study of climate over both time and space.One central goal is to determine climatic regions, areas with similar weather statistics.Another central goal is to analyze climate variability over time (like global warming!).

EcosystemsClimates influence the location of an ecosystemEcosystem: the natural, self-regulating communities formed by plants and animals in their nonliving environment.Biome: A large terrestrial ecosystem characterized by specific plant communities and formations

BiomesUsually named after the predominant vegetation in the regionExamples: savanna, forest, grassland, tundra, desertEach biome is a collection of animals, plants, and soilsBiomes constantly changing and adapting to changes in climate

Climate ClassificationProvides an organized and manageable source of information that simplifies rather complex patterns in the real worldAlso gives us a common short hand way to describe climates quickly and easilyBy using 2 principal climatic components, temperature and precipitation, general climate types are revealed

KoppenKoppen climate classificationDeveloped 1918Developed to correlate the spatial distribution of plants to the spatial distribution of climateThe Koppen-Geiger climate classification system is the updated version in your text

Köppen’s Climate Classifications

Tropical Climates (A)Average temp of every month > 18ºC

Mesothermal Climates (C)Coldest month average temperature < 18ºC but >-3ºCAt least 1 month average temperature > 10ºC

Microthermal Climates (D)Average temperature of warmest month >10ºCAverage temperature of coldest month < -3ºC

Primary Letters

Köppen’s Climate Classifications

Polar Climates (E)Average temperature of all months  < 10ºC

Dry Arid and Semiarid Climates (B)

Evaporation > precipitation

Highland (H)

Primary Letters

Köppen’s Climate ClassificationsSecondary Letters

These letters are based primarily on seasonal precipitation:

f = adequate rainfall all through the year, no distinct dry seasonw = winter dry, if 70% or more of annual rainfall occurs in summers = summer dry, if 70% or more of annual rainfall occurs in winterm = extremely wet summer = monsoon. A climate only.

Köppen’s Climate ClassificationsSecondary Letters

For B climate only:S = semiarid = steppeW = arid = desertwhich results in either BS or BW.

For E climate only:T = tundraF = perpetual frost = permanent icewhich results in either ET or EF.

Köppen’s Climate ClassificationsTertiary Letters

The third letters in the system are based exclusively on seasonal and annual temperature:

a = hot summer, warmest month > 22°C; C and D onlyb = warm summer, warmest month < 22°C; C and D onlyc = cool summer, < 4 months over 10°C; C and D onlyd = very cold winter, coldest month < -38°C; D onlyh = dry-hot, annual temperature > 18°C; B onlyk = dry-cold, annual temperature < 18°C; B only

Köppen’s Climate ClassificationsExamples of Combinations

Af = Tropical Rainforest climate typeAm = Tropical Monsoon climate typeBWh = Low-Latitude Hot Desert climate typeCfa = Humid Subtropical climate typeCsa = Mediterranean climate typeDfb = Humid Continental climate typeET = Tundra climate type

World Climate Classification

Figure 10.5

Tropical Climates (A)Tropical Rain Forest Climates (Af)  Tropical Monsoon Climates (Am)  Tropical Savanna Climates (Aw)Consistent daylength and insolation input

= consistent warm temperaturesDominance by ITCZ

Shifts seasonally with high sun periodWarm ocean currents, unstable maritime air masses

Tropical Rain Forest and Monsoon

Arid and Semiarid Climates (B)Köppen system:

W = Desert (arid), S = Steppe (semiarid)h = hot (mean annual temp > 18°C)usually found in lower latitudesk = cold/cool (mean annual temp < 18°C)usually found in the midlatitudes

Low-Latitude Hot Desert Climates (BWh)  Midlatitude Cold Desert Climates (BWk)  Low-Latitude Hot Steppe Climates (BSh)  Midlatitude Cold Steppe Climates (BSk)  

Arid and Semiarid Climates (B)

Potential for evaporation exceeds rainfall Cover 35% of Earth’s surfaceMost extensive geographically of the major climate groupsOne-third of U.S. is classified as arid/semiarid

Arid and Semiarid Climates (B)

Mesothermal Climates (C)  Humid Subtropical (Hot-Summer) Climates (Cfa)  Humid Subtropical (Winter-Dry) Climates (Cwa)Marine West Coast Climates (Cfb, Cfc)  Mediterranean Dry-Summer Climates (Csa, Csb)  

Mesothermal Climates (C)  Humid Subtropical (Hot-Summer) Climates (Cfa) C = warmest month above 10ºC, coldest month above -3ºC = seasonal climates

a = hot summer, warmest month above 22ºCf = year-round precipitationw = winter dry (> 70% of rainfall concentrated in summer months)

Humid Subtropical (Winter-Dry) Climates (Cwa) C = warmest month above 10ºC, coldest month above -3ºC = seasonal climates

a = hot summer, warmest month above 22ºCw = winter dry (> 70% of rainfall concentrated in summer months)

Mesothermal Climates (C)  

Wet winters, dry summers = “s”70% of precipitation in winter

Mediterranean Climates (Csa, Csb)

Marine West Coast ClimatesMild winters, cool summersUnusual climates for their latitude, extending close to Arctic Circle.Maritime polar air masses (mP) dominate.

Mesothermal Climates (C)  

Microthermal Climates (D)Also called “cool temperate” or “snow climates.”Average temperature of warmest month above 10°C.Average temperature of coldest month below 0°C.Distinct strong seasonality in temperature ranges throughout the year.21% of land surface in Microthermal climates.Occurs due to continental locations (cP air masses common).In Southern Hemisphere, found only in highlands.

Microthermal ClimatesHumid Continental Hot-Summer Climates

Dfa, Dwa

Humid Continental Mild-Summer ClimatesDfb, Dwb

Subarctic ClimatesSubarctic Cool-Summer: Dfc, DwcSubarctic Extreme-Winter: Dfd, Dwd

Microthermal Climates (D)Humid Continental Mild-Summer Climates (Dfb, Dwb)Found poleward of Dfa and Dwa climates.Cold temperatures in winter primarily due to:

continental locationshigher latitudescP air masses

Less precipitation than hot summer climatesHeavier snowfall

Microthermal Climates (D)Subarctic Climates (Dfc, Dwc, Dwd)

Found poleward of Dfb and Dwb climate.Extensive geographically:

North America, stretching from Atlantic to Pacific.Eurasia, stretching from Scandinavia to the Pacific.Subarctic extreme-winter found only in eastern Asia

Most extreme temperature ranges of all climatesExtremely cold temperatures in winter primarily due to:

continental locations = Siberian High in winterhigher latitudescP air masses

Microthermal Climates (D)

Polar and Highland Climates

Tundra Climate (ET)Ice Cap and Ice Sheet Climates (EF)Polar Marine Climate (aka “Polar Maritime”) EM

More moderate than other two polar climates (why?)No month below -7°C (20°F), but not as warm as tundra climateLow annual range of temperatureExists only along very fringes of highest latitudesBering Sea (Alaska, Russia), southern Greenland, northern Iceland, Norway)

Polar and Highland Climates