1. Climates and Climate Classification

2. Climate
• Climate is weather over time
• Climatology is the study of climate
• Climatic regions are areas with
similar weather statistics

3. Earth’s Climate System and Its
Classification
• Climate Components
• Classification of Climatic Regions
• A Climate Classification System

4. Climate Components
• Insolation
• Temperature
• Pressure
• Air Masses
• Precipitation

5. Earth’s Climate System

6. Climate Classification --
Two Approaches
• Empiric
– Classes are based on observations and the
effects of the phenomena
– Examples include Koeppen and Thornthwaite
• Genetic
– Classes are based on causes of the
phenomena
– Examples include Air-Mass, Synoptic
Classifications, etc.

7. The Elements of Climate
• Based on
– Temperature
– Precipitation
– Pressure
– Wind Direction/Speed
– Cloud Cover
– “Climate proxies”

8. Climographs

9. The Koeppen System
• The Major Climates
– The Tree Climates
• A - Tropical Rainy Climates
• C - Midlatitude Rainy Climates (mild winter)
• D - Midlatitude Rainy Climates (cold winter)
– Trees Don’t Grow Here
• B - Dry Climates
• E - Polar Climates

10. Generalized Climate Regions

11. Koeppen System:
Principal Climate Types
• Tropical
– Af - Tropical Wet (Rains all year)
– AW - Tropical Wet/Dry (Dry Winter Season)
– Am - Tropical Monsoon (Shorter Dry Season)
• Dry
– BW - Desert (BWh - hot desert, BWk, cold desert)
– BS - Steppe (semi-arid) BSh - hot steppe, BSk, cold steppe)
• Mesothermal
– Cfa, Cwa - Humid Subtropical
– Csa, Csb - Mediterranean
– Cfb, Cfc - Marine West Coast

12. Koeppen System:
Principal Climate Types
• Microthermal
– Dfa, Dfb Dwa, Dwb - Humid Continental
– Dfc, Dwc, Dfd, Dwd - Subarctic
• Polar
– ET - Tundra
– EF - Ice Cap (Remember, Eternally Frozen!)
• Highland Climates

13. Koeppen System: The Particulars
• First Letter -
– Designates Major Type (A, B, C, D, E)
• Second Letter
– If with A, C, or D climates, denotes seasonality of
precipitation (f - all year, w=dry winter, s=dry summer)
– If with B, denotes whether hot (h) or cold (k)
• Third Letter
– Designates different temperature regimes and
sometimes other parameters like fog frequency, etc.

14. The Factors Forming the Koeppen System
Figure 6.5

15. Tropical Climates

16. Tropical Climates
• ~ 12 hours a day throughout the year
• There is a greater daily energy change than
there is annual energy change
• Influenced by the migration of the ITCZ
• No temperature constraints on growth leading
to large species diversities

17. Movement of the ITCZ
Figure 4.11

18. Tropical Rain Forest
(Tropical Wet)
(Af)
Figure 6.6

19. Tropical Monsoon
(Am)
Figure 6.7

20. Tropical Savanna
(Tropical Wet-Dry)
(AW)
Figure 6.8

21. Dry, Arid, and Semiarid Climates
• Desert Characteristics
• Low-Latitude Hot Desert Climates
• Midlatitude Cold Desert Climates
• Low-Latitude Hot Steppe Climates
• Midlatitude Cold Steppe Climates

22. Dry, Arid, and Semiarid Climates

23. Low-Latitude Hot Desert
(BWh)
Figure 6.21

24. Low-Latitude Hot Steppe
(BSh)
Figure 6.23

25. Midlatitude Cold Desert
(BWk)
Figure 6.22

26. Midlatitude Cold Steppe
Figure 6.24

27. Mesothermal Climates
• Humid Subtropical
– Hot, Humid Summer
• Marine West Coast
– Mild All Year, No Dry Season
• Mediterranean
– Dry Summer

28. Mesothermal Climates

29. Humid Subtropical
Hot-Summer
(Cfa)
Figure 6.9

30. Marine West Coast
(Cfb, Cfc)
Figure 6.11

31. Marine West Coast
(Cfc)
Figure 6.12

32. Mediterranean Climates
(Csa, Csb)
Figure 6.14

33. Microthermal Climates
• Humid Continental Hot-Summer
Climates
• Humid Continental Mild-Summer
Climates
• Subarctic Climates

34. Microthermal Climates

35. Humid Continental Hot-Summer (Dfa, Dwa)

36. Humid Continental Mild-Summer (Dfb, Dwb)
Figure 6.16

37. Subarctic (Dfc, Dwc)
Figure 6.17

38. Subarctic (Dfd, Dwd)
Figure 6.18

39. Polar Climates (ET, EF)
• Tundra Climate
• Ice Cap and Ice Sheet Climates
– Polar Marine Climate

40. Polar and Highland Climates

41. Hypothetical
Climate Model
http://www.colorado.edu/geography/class_homepages/geog_1001_s06/HypoContinent.pdf

42. Reality

43. Climate Classification – The Genetic
Approach
• Based on what causes climates, not
based on categories determined by
observations
• For example….

44. General Atmospheric Circulation and
Climate Regimes
Polar Transitional Arid Tropical
Figure 4.13

45. Genetic Classification Scheme:
An Air-Mass Dominance Example
Wet All Year Wet /Dry Dry All Year
Equatorial Low Subtropical High
Warm 1 2 3
mT cT
Seasonal 6
4 5
mP cP
Cold 7 8 9
Subpolar Low Polar High

46. Climates and Water Resource Issues

47. “When the well is dry, we know the worth
of water…”
- Benjamin Franklin
Robert W. Christopherson
Charlie Thomsen

48. Water Resources
– Soil - Water budget concept
– Water availability
– Soil moisture availability

49. Ocean and Freshwater Distribution
Figure 5.3

50. Hydrologic Cycle Model -
Revisited
Figure 7.1

51. The Hydrologic Cycle
• A Hydrologic Cycle
Model
– More Evaporation over
Oceans than over Land
– More Precipitation over
land than over oceans
– Amount of water
advected to the land
equals the amount
runoff back to the
oceans
• Surface Water
– Only .333% of all
surface fresh water is
available for human
use.
– 11.20% of all fresh
water is available for
human use in
groundwater and soil
moisture

52. The Soil-Water Balance Equation
Figure 7.2

53. Surface-Moisture Environment
Figure 7.2

54. Remember…
• If the air rises, it’s more likely to rain (or snow…)
• Where it sinks, it’s less likely to rain (or snow…)
• The less rainfall you have…
– The less reliable it is
• So, a climate with a dry season, isn’t necessarily
guaranteed a wet season either!
– Monsoon climates
– Steppe and Savannah Climates
– Deserts (obviously)

55. Precipitation in North America
Figure 7.4

56. Potential Evapotranspiration
Figure 7.6

57. Lysimeter
Figure 7.5

58. Types of Soil Moisture
Figure 7.7

59. Sample Water Budget
Figure 7.9

60. Sample Water Budgets
Figure 7.10

61. Annual Global River Runoff
Figure 7 .11

62. Groundwater Resources
• Groundwater Profile and Movement
• Groundwater Utilization
• Pollution of Groundwater
Resources

63. Groundwater Potential
Figure 7.12

64. Groundwater Characteristics
Figure 7.13

65. Groundwater Characteristics
Figure 7.13

66. High Plains Aquifer Overdraft
Figure 1

67. Our Water Supply
• Water Supply in the United States
• Instream, Nonconsumptive, and
Consumptive Uses
• Future Considerations

69. U.S.
Water Budget
1. Three-fourths
of what falls
is evaporated
2. We withdraw
and consume
one-third of
what is left on
a one-time
basis
3. Some of the
water is
exchanged
into
groundwater
which might
not be
recoverable
Figure 7.17

70. Water Withdrawal by Sector
Figure 7.18

71. Global Water Scarcity
Figure 7.19

72. Future Considerations
• There’s plenty of water (if you like salt with your
water!) and we don’t loose any of it…
• On a local basis, water resource scarcity is a very real
issue
• Too much water and the water becomes polluted
• Too little water and the water becomes polluted
• Water scarcity globally are major issues where:
1. The water is used mostly for agriculture and thus for growing
the food supply and…
2. Where competing regions are sharing the same water supply

73. Global Climate Change
• Global Warming
• Climate Models and Future
Temperatures
• Consequences of Global Warming
• Political Action to Slow Global
Warming

74. Global Temperatures

75. 1998 Temperature Anomalies

77. CO2 Sources

78. GCM Model

79. 2070-2100 Temperature Forecast
Versus 1961-1990 Global Average

80. “You want proof?”

81. Then there’s the other side of the argum

82. Stephen Schneider (1945-2010) Comment

83. What thinkest thou?