Chapter 12: Global Climate

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

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

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.

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) 20-40 yrs, c) 40-60 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 Vegetation type: chaparral (includes Chamise, manzanita, and foothill pine) • Mediterranean (Cs):

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