Transcript Document

Chapter 12: Global Climate
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A world with many climates
Climatic classification - the Köppen system
The global pattern of climate
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Global Temperatures
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controls on temperature climatology:
- intensity of sunshine and its variation with latitude
- distribution of land and water and ocean currents
- prevailing winds
- location of high and low pressure areas
- mountain barriers and altitude
Q: The Antarctic in the next slide is not so cold, because
a) winter and summer average out
b) Antarctic is actually not too cold compared to Arctic
c) only the equivalent sea-level temperature is shown
d) Arctic is simply colder
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Average annual sea-level temperature
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Global Precipitation
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relationship to areas of rising and sinking air
• Precipitation is most abundant where air rises,
and least abundant where it sinks.
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influence of ITCZ
influence of
orographic uplift
and rain shadows
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mm/month
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Climatic Classification - the Köppen
System (1918)
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Tropical moist climates
dry climates
moist midlatitude climates with mild winters
moist midlatitude climates with severe winters
polar climates
mountains
criticisms of the Köppen climate classification system: sharp
boundary between climatic zones due to the use of vegetation
to represent monthly temperature and precipitation.
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The Global Pattern of Climate
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Major features of Earth’s climate distribution (moist tropical, dry,
moist/mild winter, moist/severe winter, polar, highland)
local variations within larger climate regions
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Tropical Moist Climates
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tropical wet (Af): rainforest; small seasonal
temperature variation; soil nutrients from dead tree
decomposition
tropical monsoon (Am): rainforest,
with 1-2 dry months
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Tropical Moist Climates
tropical wet and dry (Aw): savanna;
distinct dry season; larger seasonal
temperature variation
Q: Why does max P occur in summer?
a) ITCZ is located there in summer
b) temperature is higher
c) vegetation needs water in summer
d) dust storm is less
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Dry Climates
In general, minimal P, large T seasonal variation, high T
 arid (BW): most of the deserts in the world;
few deserts are completely barren; xerophytes
Q: What is the age of the cactus with arms in the figure?
a) 0-20 yrs, b) 20-40 yrs, c) 40-60 yrs, d) > 60 yrs
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Dry Climates
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semiarid (BS) or steppe: most of western U.S. (including
Tucson); grass or shrubs
Q: is it possible to have coastal
deserts with clouds and drizzles in
the world?
a) yes; b) no
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Moist Subtropical Mid-Latitude Climates
humid with mild winters; relatively large T variation
 humid subtropical (CfA): SE U.S.; small P seasonal variation
 (west coast) marine (CfB): cool summer
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Moist Subtropical Mid-Latitude Climates
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Mediterranean (Cs): dry summer; western coast of U.S.;
coastal areas of the Mediterranean Sea
coastal
Cs
interior
Cs
Q: why is summer so dry in San Francisco? a) subtropical high;
b) foggy weather, c) cold temperature, d) cloudy sky
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Moist Subtropical Mid-Latitude Climates
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Mediterranean (Cs):
Vegetation type: chaparral (includes Chamise, manzanita, and
foothill pine)
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Moist Continental Climates with
Severe Winter
Hot summer
Dfa
Cool summer
Dfb
Subpolar
Dfc
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Polar Climates
Tundra (ET)
ice caps (EF)
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Highland Climates
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altitude effects are similar to latitude effects:
100 m elevation difference ~ 1 deg in horizontal distance
Across central Sierra Nevada
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Q: Semi-arid regions usually have
a) grassland and/or shrubland,
b) forest,
c) tundra
Q: Mediterranean climate usually has
a) shrubland,
b) grassland, c) chaparral, d) forest
Q: Humid continental climate with severe winter and cool
summer usually has
a) boreal forest, b) grassland, c) shrubs
Q: Subpolar or polar climate usually has
a) forest, b) tundra
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