Climatic Controls
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Latitude
Altitude
Continentality
Prevailing Wind
Air Mass Variability
Topography
Ocean Currents
Land Use / Land Cover Change
Empiric classification:
Köppen and later modified by
Thornthwaite and Trewartha
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looked at the global distribution of different
plant and animal species and attempted to
see how weather variables correlated with
these patterns.
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Temperature and precipitation
Köppen climate classification
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Five primary categories
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A Tropical
B Dry
C Mesothermal- “moderate”
D Microthermal- “low”
E Polar
BASIC WORLD CLIMATES
A climates
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Mean temperature of coldest month is above
18°C (64°F)
Essentially, no freezes
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Tropical Rainy: no dry season
Tropical Wet-and-Dry: short dry season
Tropical Monsoon: long dry season
TROPICAL RAINFOREST
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Annual precip > 80”
No real seasons
Sticky, humid air, with little wind
High sun angle all year
Tropical Savanna and Monsoon
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Savanna
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Monsoon
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alternating 3 month wet and dry periods
dominated by movement of ITCZ
5 - 7 month wet and dry regime
Both have 40 – 80” precip/year and average
temps above 64°F every month
B climates
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Arid and Semi-arid
P < PE
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BW (Desert):
BS (Steppe):
Steppes
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Dry short grass regions surrounding deserts
There are cold and hot steppes
Hot steppes are subtropical
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Cold steppes are at mid latitudes
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South Texas
Montana
Both have approximately 10 – 20” annual
precip
Deserts
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Hot and Cold deserts just like Steppes
Both have < 10” precip/year
Abundant sunshine
Hot desert
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Sahara
Cold desert
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Gobi
C climates
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Essentially, it freezes but snow is not
permanently on the ground in winter.
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Mediterranean: dry summer
Wet-and-dry: dry winter
Humid: no dry season
Humid Subtropical
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Mild winters with temperatures frequently
dipping below freezing (northern limits) to
infrequent freezes (southern limits)
Hot summers
Abundant precip throughout the year
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SE U.S.
Mediterranean
(dry summer subtropical)
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No summer rain
Very little late spring/early fall rain
Cool moist winters and warm summers
Climate moderated by cold water
Abundant sunshine
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Southern Cal
Marine West Coast
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Cool/cold and moist winters
Pleasant summers with temps generally not
exceeding 85°F
Summer is drier
Persistent fog, drizzle, gray skies for the
majority of the year
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Seattle, London
D climates
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Coldest month is less than -3°C; warmest
month above 10°C.
Essentially, where snow remains on the
ground for part of the winter.
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Wet-and-dry: dry winter
Humid: no dry season
Humid Continental
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Cold winters and warm summers
Precip in every month
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Northern U.S.
Humid Continental (cool summers)
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Located farther north with colder winters
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Southern canada
Subarctic Boreal or Taiga
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Brutal winters
Coniferous forests
Short cool summer with average temps
breaking 50F and frequently reaching the
70s
Not much precip 10 – 20”
Northern Hemisphere only
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Most of Canada, Russia
E climates
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Warmest month below 10°C.
Essentially, where it’s too cold for trees to
grow
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Tundra: it thaws in summer
Ice Cap: it doesn’t
Tundra and Icecap
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Tundra is treeless
Average temps do not break 50°F
Small flowering plants, lichens, mosses,
Horrible insects in summer when permafrost thaws
Icecap is frozen year round
Occasionally temperatures will rise above freezing
Alpine or Highland
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Complex climates because of altitude
Can be a little of everything depending on
the elevation
WORLD CLIMATES
ANNUAL PRECIP