1. Chapter 9 Water Resources
Geosystems 6e
An Introduction to Physical Geography
Robert W. Christopherson
Charles E. Thomsen

2. Chapter 9
You are responsible for pages in chapter 9

3. Water Constantly cycling through the environment
Water 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

4. Water Budget

5. 97% of Earth’s water in the ocean, so most precipitation and evaporation takes place there
The bulk of global precipitation comes from ocean water

6. 86% of all evaporation traced to ocean
14% of all evaporation traced to the land

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

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

9. Water spends 10 days (on average) in the atmosphere
Water spends 3,000-10,000 years in deep-ocean circulation, groundwater aquifers, glacial ice

11. Geosystems 6e An Introduction to Physical Geography
End of Chapter 9
Geosystems 6e
An Introduction to Physical Geography
Robert W. Christopherson
Charles E. Thomsen

12. Chapter 10 Global Climate Systems
Geosystems 6e
An Introduction to Physical Geography
Robert W. Christopherson
Charles E. Thomsen

13. Climate
Climate 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!).

14. Ecosystems Climates influence the location of an ecosystem
Ecosystem: 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

15. Biomes Usually named after the predominant vegetation in the region
Examples: savanna, forest, grassland, tundra, desert
Each biome is a collection of animals, plants, and soils
Biomes constantly changing and adapting to changes in climate

16. Climate Classification
Provides an organized and manageable source of information that simplifies rather complex patterns in the real world
Also gives us a common short hand way to describe climates quickly and easily
By using 2 principal climatic components, temperature and precipitation, general climate types are revealed

17. Koppen Koppen climate classification Developed 1918
Developed to correlate the spatial distribution of plants to the spatial distribution of climate
The Koppen-Geiger climate classification system is the updated version in your text

18. Köppen’s Climate Classifications
Primary Letters
Tropical Climates (A)
Average temp of every month > 18ºC
Mesothermal Climates (C)
Coldest month average temperature < 18ºC but >-3ºC
At least 1 month average temperature > 10ºC
Microthermal Climates (D)
Average temperature of warmest month >10ºC
Average temperature of coldest month < -3ºC

19. Köppen’s Climate Classifications
Primary Letters
Polar Climates (E)
Average temperature of all months  < 10ºC
Dry Arid and Semiarid Climates (B)
Evaporation > precipitation
Highland (H)

20. Köppen’s Climate Classifications
Secondary Letters
These letters are based primarily on seasonal precipitation:
f = adequate rainfall all through the year, no distinct dry season
w = winter dry, if 70% or more of annual rainfall occurs in summer
s = summer dry, if 70% or more of annual rainfall occurs in winter
m = extremely wet summer = monsoon. A climate only.

21. Köppen’s Climate Classifications
Secondary Letters
For B climate only:
S = semiarid = steppe
W = arid = desert
which results in either BS or BW.
For E climate only:
T = tundra
F = perpetual frost = permanent ice
which results in either ET or EF.

22. Köppen’s Climate Classifications
Tertiary 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 only
b = warm summer, warmest month < 22°C; C and D only
c = cool summer, < 4 months over 10°C; C and D only
d = very cold winter, coldest month < -38°C; D only
h = dry-hot, annual temperature > 18°C; B only
k = dry-cold, annual temperature < 18°C; B only

23. Köppen’s Climate Classifications
Examples of Combinations
Af = Tropical Rainforest climate type
Am = Tropical Monsoon climate type
BWh = Low-Latitude Hot Desert climate type
Cfa = Humid Subtropical climate type
Csa = Mediterranean climate type
Dfb = Humid Continental climate type
ET = Tundra climate type

24. World Climate Classification
Figure 10.5

25. Tropical Climates (A) Tropical Rain Forest Climates (Af)
Tropical Monsoon Climates (Am)  
Tropical Savanna Climates (Aw)
Consistent daylength and insolation input
= consistent warm temperatures
Dominance by ITCZ
Shifts seasonally with high sun period
Warm ocean currents, unstable maritime air masses

26. Tropical Rain Forest and Monsoon

27. Arid and Semiarid Climates (B)
Köppen system:
W = Desert (arid), S = Steppe (semiarid)
h = hot (mean annual temp > 18°C)
usually found in lower latitudes
k = 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)  

28. Arid and Semiarid Climates (B)
Potential for evaporation exceeds rainfall
Cover 35% of Earth’s surface
Most extensive geographically of the major climate groups
One-third of U.S. is classified as arid/semiarid

29. Arid and Semiarid Climates (B)

30. 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)  

31. 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 22ºC
f = year-round precipitation
w = winter dry (> 70% of rainfall concentrated in summer months)

32. Mesothermal Climates (C)
Humid Subtropical (Winter-Dry) Climates (Cwa) C = warmest month above 10ºC, coldest month above -3ºC = seasonal climates
a = hot summer, warmest month above 22ºC
w = winter dry (> 70% of rainfall concentrated in summer months)

33. Mediterranean Climates (Csa, Csb)
Wet winters, dry summers = “s”
70% of precipitation in winter
Marine West Coast Climates
Mild winters, cool summers
Unusual climates for their latitude, extending close to Arctic Circle.
Maritime polar air masses (mP) dominate.

34. Mesothermal Climates (C)

35. 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.

36. Microthermal Climates
Humid Continental Hot-Summer Climates
Dfa, Dwa
Humid Continental Mild-Summer Climates
Dfb, Dwb
Subarctic Climates
Subarctic Cool-Summer: Dfc, Dwc
Subarctic Extreme-Winter: Dfd, Dwd

37. 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 locations
higher latitudes
cP air masses
Less precipitation than hot summer climates
Heavier snowfall

38. 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 climates
Extremely cold temperatures in winter primarily due to:
continental locations = Siberian High in winter
higher latitudes
cP air masses

39. Microthermal Climates (D)

40. 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 climate
Low annual range of temperature
Exists only along very fringes of highest latitudes
Bering Sea (Alaska, Russia), southern Greenland, northern Iceland, Norway)

41. Polar and Highland Climates