Chapter 13: Global
Climate
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A world with many climates
Climatic classification - the Köppen system
The global pattern of climate
Global Temperatures
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Controls on climate:
- intensity of sunshine and its variation with
latitude
- distribution of land and water
- ocean currents
- prevailing winds
- location of high and low pressure areas
- mountain barriers
- altitude
Fig. 13-1, p. 355
Global Temperatures
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“Bending” of isotherms near the continents
Isotherms are west to east (solar radiation)
Coldest temperatures over the interior of
continents, warmest in subtropical deserts
Global Precipitation
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Where air is rising, expect rain. Sinking
air, expect a dry climate
ITCZ produces a tremendous amount of
rain
Influence of orographic uplift and rain
shadows
Fig. 13-2, p. 356
Stepped Art
Fig. 13-2, p. 356
Climatic Classification - the
Köppen System
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Tropical moist climates - average temp. Always above
64°F. Basically no winter
Dry climates – deficient precipitation. Evaporation and
transpiration greater than precipitation
Moist midlatitude climates with mild winters – warm-tohot summers, mild winters. Ave. temps. coldest month
between 64°F and 27°F
Moist midlatitude climates with severe winters – warm
summers and cold winters. Ave. temps warmest month
between 50°F and 27°F
Polar climates – Extremely cold winters and summers.
Ave temp between 50°F in warmest month. No summer.
Climatic Classification - the
Köppen System
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Criticized because:
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Boundaries do not relate to natural boundaries in
climatic zones
System implies sharp changes. In reality, they are
more subtle
Fig. 13-6, p. 361
Stepped Art
Fig. 13-6, p. 361
The Global Pattern of Climate
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Climate regions vary due to local effects
Tropical Moist Climates
rain
(Group A) • Tropical
forests and monsoons
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Tropical wet
(Af)
Warm all
seasons
Lots of rain
N and S of
equator to 15°
to 25°
Rainfall greater
than 59 in.
are included in this
category.
Tropical Moist Climates
(Group A)
Tropical Moist Climates
(Group A)
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Tropical monsoon (Am)
Precip drops below 6 cm for one or two
months
 Annual precipitation amounts are similar to Af
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Tropical Moist Climates
(Group A)
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Tropical wet and dry (Aw)
Distinct dry season
Jungle can not survive
 Savanna grass
Dry Climates (Group B)
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Arid (Bw)
 Deficient precipitation
 Sonoran and Mojave deserts (Rain shadow)
Dry Climates (Group B)
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Semiarid (BS)
Transition between arid
and more humid climates
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Moist Subtropical Mid-latitude
Climates (Group C)
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Humid subtropical (CfA)
Humid and mild winters
 Eastern and western
Regions of most continents
 Hot, muggy summers
 Mild winters
 Snowfall is rare
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Moist Subtropical Mid-latitude
Climates (Group C)
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Marine (CfB)
Summers are
cool
Long summers
Mountains that
parallel coast
have effect
Clouds and
drizzle
Moist Subtropical Mid-latitude
Climates (Group C)
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Mediterranean (Cs)
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Dry summers, influenced by the subtropical
highs
Moist Continental Climates
(Group D)
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Warm to cool summers, cold winters
Winters are severe (cold, snowstorms)
Controlled by large landmasses (N.H.)
Coldest month average below 27°F
Can still have trees
Moist Continental Climates
(Group D)
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Humid continental with hot summers (Dfa)
Latitude 40°N to 50°N
 Precipitation between 20 and 40 in.
 Hot summers (exceed 90°F)
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Moist Continental Climates
(Group D)
Humid continental with cool summers (Dfb)
 Cooler and less
humid than Dfa
 Hot spells shorter
 Winters long, cold
windy
 Large
temperature
range like Dfa
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Moist Continental Climates
(Group D)
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Subpolar (Dfc)
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Severe winters, short summers
Only 1 month w/ mean temp > 50°F
Large temperature ranges
Precipitation is light
Boreal climate
Polar Climates (Group E)
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Always low temperatures
One type has at least one month above
freezing…one doesn’t
Polar Climates (Group E)
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Polar tundra (ET)
 Always low temperatures (warmest month < 50°F
 Permafrost is abundant/Low precipitation amounts
 Tundra vegetation (mosses, scattered wooded areas
 Large temperature ranges
Polar Climates (Group E)
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Polar ice caps (EF)
Average temp always
below freezing
No plants
Covered in snow and
ice
Little precipitation
Katabatic winds
present
Highland Climates (Group H)
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Altitude effects are similar to latitude
effects