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Chapter 7
Global Climates
60
Climate
- What is climate?
- “Characteristic pattern of average weather elements
over a period at a location”
- Measurements to utilize:
- Daily NR
- Pressure
- Wind Speed
- Cloud Cover
- Remember: 3 main elements influence air temperature:
- 1. Latitude
- 2. Maritime/Continental Climate
- 3. Elevation
Temperature Regimes
• Temperature Regimes- distinctive types of
annual temperature cycles related to latitude
and location
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Equatorial
Tropical
Midlatitude
Subarctic
*Continental vs. Maritime
Ex: Cameroon vs. Algeria
Global Precipitation
• Categories
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1.
2.
3.
4.
5.
6.
7.
Wet Equatorial Belt
Trade Wind Coasts
Tropical Deserts
Midlatitude Deserts and Steppes
Moist Subtropical Regions
Midlatitude West Coasts
Arctic and Polar Deserts
Precipitation Variability
• Why is variation is precipitation on an
annual basis important?
– Uniformity vs. non-uniformity = Different
vegetation and landscape
• 3 types of monthly precipitation patterns:
– 1. Uniform distribution of precipitation
– 2. Precipitation max. during Summer
– 3. Precipitation max. during Winter
Applications of Climatology
• Classification
• Solving “operational problems,” such as for
agricultural purposes
• Prediction – what can we expect?
• Analysis – why did something happen?
• Improved understanding of human impacts
on the environment
A Quick Example
• Analysis of particulate matter (PM)
• Obtained PM measurements from sites around
Tucson
• Looked at weather conditions for certain cases
• Wanted to determine how atmospheric circulation
patterns affected PM levels
• Determined which patterns generally produced
higher PM measurements
Climographs
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• Graph showing means
of temp and precip by
month for a location
• Line – temp
• Bars – precip
• Often indicate total
annual precip and
mean annual temp
• What info is revealed?
Classification Schemes
• Provide a short-hand that allows scientists
to recognize climatic conditions and
characteristics
• Use a variety of data to determine climate
types
• Numerous schemes ranging from
general/global to very specific, projectoriented and regional
Some Classification Schemes
• Grosswetter – focuses on large-scale atmospheric
circulation patterns and how they steer weather
systems
• Strahler – utilizes characteristics of atmospheric
circulation and air masses
• Thornthwaite – based on vegetation type, and
measurements of temp, precip, and moisture available
for plant growth
• Köppen
– considers temperature and precipitation that relate
to transition between vegetation types
– most popular/well-known
– uses five main climate types (A, B, C, D, E)
3 Groups of Climates
• Group 1- Low-Latitude Climates (4)
– Dominated by cT, mT, and mE
– Influence by ITCZ and subtropical H pressure
• Group 2- Mid-Latitude Climates (6)
– Intense interaction between unlike air masses
– Wave cyclones are common
• Group 3- High-Latitude Climates (3)
– Polar and Arctic air masses
Dry vs. Moist Climates
• Dry climates
– “When total annual evaporation from soil/plants
exceeds annual precip”
– 2 categories:
• 1. Semi-arid (Steppe)
• 2. Arid
• Moist climates
– “Those climates with sufficient rainfall to maintain the
soil in a moist condition throughout the year”
• 2 of 13 climate types cannot be classified as dry or moist:
– 3—Wet-Dry Tropical
– 7—Mediterranean
Low-Latitude Climates
• General information:
– Lie between Tropics of Cancer/Capricorn
– Accompany the ITCZ and belt of Tropical Easterlies
• 1. Wet Equatorial Zone
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Dominated by mE and mT
Heavy rainfall
Mean temp of 81°F
Found between 10°N/S
Amazon, Congo, East Indies
Low-Latitude Climates
• 2. Monsoon and Trade-Wind Coastal
Climate
– Unlike #1, this climate has a Seasonal pattern
of rainfall due to migration of ITCZ
– Between 5-25°N/S
– 2 different situations responsible for similar
climate
– Central/South America, Caribbean, SE Asia,
India
Low-Latitude Climates
• 3. Wet-Dry Tropical Climate
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Just North of #2 Climate
Winter (cT), Summer (mT and mE)
5-20°N/S
Example: Guinea
Vegetation: Savannah
Low-Latitude Climates
• 4. Dry-Tropical Climate
– Found in center and East sides of subtropical
H pressure
– Rainfall=Rare
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15-25°N/S
Examples: Sahara, central Australia, Western SA
Steppes
Figure 7.18
Mid-Latitude Climates
• General Information:
– Almost all mid-latitude climates are in N hem.
– Zone of interaction (mT vs. mP/cP)
• 5. Dry Subtropical Climate
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Poleward extension of #4, but with greater temp. range
TUCSON
Plants/Trees
Freezing temps
North/South Africa, Mojave/Sonoran Deserts
Mid-Latitude Climates
• 6. Moist Subtropical Climate
– Subtropical H pressure provides warm, moist
air on Eastern sides of continents
– Tropical cyclones
– Convection-based rainfall
– 20-35°N/S
– Examples: Southern China, US(SE)
• Charleston, SC
– Vegetation
Mid-Latitude Climates
• 7. Mediterranean Climate
– Reason: Poleward mov’t of subtropical
H pressure during Summer
– Location along West coasts
– Summer (cT), Winter (mP)
– 30-45°N/S
– Monterrey, CA
– Vegetation (Adaptation to survive for dry part
of year)
Mid-Latitude Climates
• 8. Marine West-Coast Climate
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Midlatitude West coasts
Westerly winds from oceans = mP air masses
Small annual temp range
Oregon/Washington, BC, Portugal, France
35-60°N/S
Vegetation: Large, expansive forests
Mid-Latitude Climates
• 9. Dry Midlatitude Climate
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Interior regions of N. America and Eurasia
Rainshadow areas—Mountain ranges W or S
cP (Winter)
Large range in annual temps
Dry, interior West (Great Basin, Columbia
Plateau, Great Plains)
Mid-Latitude Climates
• 10. Moist Continental Climate
– Winter (Cold, cP, cA) and Summer (Mild, mT)
– 45-60°N/S
– Middle Europe, middle U.S, and Northern
China
High-Latitude Climates
• 11. Boreal Forest Climate
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Source region for cP
Invasion by cA COMMON
Great temp. range
Precip. Increase during summer
Alaska, Canada, middle Russia
High-Latitude Climates
• 12. Tundra Climates
– Dominated by cP, mP, and cA
– Winters are long/severe
– Northern Canada, edges of Greenland, northern
Russia
– 60-75°N/S
– Summer=Short period w/ above freezing temps
– “Tundra”
High-Latitude Climates
• 13. Ice Sheet Climate
– No mean monthly temp above freezing
– 65-90°N/S