Climates and Climate Classification

Climate

• Climate is weather over time

• Climatology is the study of climate

• Climatic regions are areas with similar weather statistics

Earth’s Climate System and Its Classification  

• Climate Components

• Classification of Climatic Regions  

• A Climate Classification System  

Climate Components

• Insolation

• Temperature

• Pressure

• Air Masses

• Precipitation  

Earth’s Climate System

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.

The Elements of Climate

• Based on– Temperature– Precipitation– Pressure– Wind Direction/Speed– Cloud Cover– “Climate proxies”

Climographs

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

Generalized Climate Regions

Figure 6.4

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

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

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.

The Factors Forming the Koeppen System

Figure 6.5

Tropical Climates

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

Figure 4.11

Movement of the ITCZ

Tropical Rain Forest(Tropical Wet)

(Af)

Figure 6.6

Tropical Monsoon(Am)

Figure 6.7

Figure 6.8

Tropical Savanna(Tropical Wet-Dry)

(AW)

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   

Dry, Arid, and Semiarid Climates   

Low-Latitude Hot Desert(BWh)

Figure 6.21

Low-Latitude Hot Steppe(BSh)

Figure 6.23

Midlatitude Cold Desert(BWk)Figure 6.22

Midlatitude Cold Steppe

Figure 6.24

Mesothermal Climates   

• Humid Subtropical – Hot, Humid Summer

• Marine West Coast – Mild All Year, No Dry Season 

• Mediterranean – Dry Summer

Mesothermal Climates  

Figure 6.9

Humid Subtropical Hot-Summer

(Cfa)

Figure 6.11

Marine West Coast(Cfb, Cfc)

Figure 6.12

Marine West Coast(Cfc)

Mediterranean Climates(Csa, Csb)

Figure 6.14

Microthermal Climates

• Humid Continental Hot-Summer Climates

• Humid Continental Mild-Summer Climates  

• Subarctic Climates

Microthermal Climates

Humid Continental Hot-Summer (Dfa, Dwa)

Humid Continental Mild-Summer (Dfb, Dwb)

Figure 6.16

Subarctic (Dfc, Dwc)

Figure 6.17

Subarctic (Dfd, Dwd)

Figure 6.18

Polar Climates (ET, EF)

• Tundra Climate 

• Ice Cap and Ice Sheet Climates– Polar Marine Climate  

Polar and Highland Climates

Hypothetical Climate Model

http://www.colorado.edu/geography/class_homepages/geog_1001_s06/HypoContinent.pdf

Reality

Climate Classification – The Genetic Approach

• Based on what causes climates, not based on categories determined by observations

• For example….

General Atmospheric Circulation and Climate Regimes

Figure 4.13

TropicalAridTransitionalPolar

Genetic Classification Scheme:An Air-Mass Dominance Example

Wet All Year Wet /Dry Dry All Year

Warm

Seasonal

Cold

1

7

4 5 6

2 3

98

Equatorial Low

Subpolar Low

Subtropical High

Polar High

mT

mP cP

cT

Climates and Water Resource Issues

Robert W. ChristophersonCharlie Thomsen

“When the well is dry, we know the worth of water…”

- Benjamin Franklin

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

Ocean and Freshwater Distribution

Figure 5.3

Hydrologic Cycle Model - Revisited

Figure 7.1

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 

The Soil-Water Balance Equation

Figure 7.2

Surface-Moisture Environment

Figure 7.2

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)

Precipitation in North America

Figure 7.4

Potential Evapotranspiration

Figure 7.6

Lysimeter

Figure 7.5

Types of Soil Moisture

Figure 7.7

Sample Water Budget

Figure 7.9

Sample Water Budgets

Figure 7.10

Annual Global River Runoff

Figure 7 .11

Groundwater Resources  

• Groundwater Profile and Movement  

• Groundwater Utilization  

• Pollution of Groundwater Resources  

Groundwater Potential

Figure 7.12

Groundwater Characteristics

Figure 7.13

Groundwater Characteristics

Figure 7.13

High Plains Aquifer Overdraft

Figure 1

Our Water Supply 

• Water Supply in the United States  

• Instream, Nonconsumptive, and Consumptive Uses  

• Future Considerations

U.S. Water Budget

Figure 7.17

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

Water Withdrawal by Sector

Figure 7.18

Global Water Scarcity

Figure 7.19

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

Global Climate Change  

• Global Warming  

• Climate Models and Future Temperatures  

• Consequences of Global Warming  

• Political Action to Slow Global Warming

Global Temperatures

Figure 6.25

1998 Temperature Anomalies

CO2 Sources

Figure 6.26

GCM Model

2070-2100 Temperature ForecastVersus 1961-1990 Global Average

Figure 6.28

“You want proof?”

Figure 6.29

Then there’s the other side of the argument…

Stephen Schneider (1945-2010) Comments on the Climate Change Debate…

What thinkest thou?