1. Chapter 12: Global Climate
A world with many climates
Climatic classification - the Köppen system
The global pattern of climate

2. Global Temperatures
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

3. Average annual sea-level temperature
Figure 13.1: Average annual sea-level temperatures throughout the world (°F).

4. Global Precipitation relationship to areas of rising and sinking air
influence of ITCZ
influence of
orographic uplift
and rain shadows
mm/month
Precipitation is most abundant where air rises, and least abundant where it sinks.

5. Climatic Classification - the Köppen System (1918)
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.

6. Figure 13.6: A simplified overview of the major climate types according to Köppen, along with some of the climatic controls. The large Hs on the map represent the average position of the subtropical high pressure areas. The solid red lines show the average position of the intertropical convergence zone (ITCZ) in January and July. The ocean currents in red are warm, whereas those in blue are cold.

7. The Global Pattern of Climate
Major features of Earth’s climate distribution (moist tropical, dry, moist/mild winter, moist/severe winter, polar, highland)
local variations within larger climate regions

8. Tropical Moist Climates
tropical wet (Af): rainforest; small seasonal temperature variation; soil nutrients from dead tree decomposition
tropical monsoon (Am): rainforest,
with 1-2 dry months

9. 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

10. 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) yrs, c) yrs, d) > 60 yrs

11. Dry Climates
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

13. 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

14. Moist Subtropical Mid-Latitude Climates
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

15. Moist Subtropical Mid-Latitude Climates
Mediterranean (Cs):
Vegetation type: chaparral (includes Chamise, manzanita, and foothill pine)

16. Moist Continental Climates with Severe Winter
Hot summer
Dfa
Cool summer Subpolar
Dfb Dfc

17. Polar Climates
Tundra (ET)
ice caps (EF)

18. Highland Climates altitude effects are similar to latitude effects:
100 m elevation difference ~ 1 deg in horizontal distance
Across central Sierra Nevada

19. 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