1. Class #31: Wednesday, November 10, 2010 1 Class #31: Wednesday, November 10 Climate types of the present

2. Class #31: Wednesday, November 10, 2010 2 Climate Is to weather what a friend’s personality is to his/her mood Sums up the weather’s long-term behavior Is the collective state of the atmosphere for a given place over a specified interval of time

3. Class #31: Wednesday, November 10, 2010 3 Climate is defined by Location –Globe, continent, region, city –Chapter 14: regional and global scale Time: a specified interval –30 year average is normal –100 years or longer for history of climate Averages and extremes of variables –Chapter 14: temperature and precipitation

4. Class #31: Wednesday, November 10, 2010 4 Controls on climate Similar to controls on temperature in Chapter 3 Latitude: solar energy input Elevation: air temperature, snow vs. rain Topography: moist vs. dry, temperature, distribution of cloud patterns, solar energy reaching the surface

5. Class #31: Wednesday, November 10, 2010 5 Controls on Climate (continued) Proximity to large bodies of water –Thermal properties of water (absorption, heat capacity, transparency, mixing) moderate temperature downwind Prevailing atmospheric circulation –Intertropical Convergence Zone (ITCZ) –Subtropical Highs

6. Class #31: Wednesday, November 10, 2010 6 Classifying Climate Hard to do –No clear boundaries –Complex natural systems How it is done –Important to life: hot or cold; moist or dry –Most common system: based on vegetation Köppen climate classification scheme based on vegetation and temperature

7. Class #31: Wednesday, November 10, 2010 7 Köppen (KEPP-in) Scheme Modified by Trewartha and Horn Related to geography and global circulation Uses letters (1, 2 or 3) in Chapter 14 Has many other subdivisions within the categories shown in our book Has 6 major groups: A, B, C, D, E, H

8. Class #31: Wednesday, November 10, 2010 8 The 6 major climate groups A: Tropical moist B: Dry (can be subtropical or mid latitude) C: Moist with mild winters (mid latitude) D: Moist with severe winters (mid latitude) E: Polar (high latitude) H: Highland (rapid climate change with elevation) 2 nd letter: usually latitude (except B) 3 rd letter: differences in temperature

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12. Class #31: Wednesday, November 10, 2010 12 Tropical Humid Climates: Af, Aw, Am All tropical (A) climates are humid Letter “f” means no dry season, rain year round, usually closest to the equator Letter “m” means “monsoonal”, with a short dry season and a very rainy season Letter “w” means “winter dry season” except no real winter in tropics, just cool

13. Class #31: Wednesday, November 10, 2010 13 Tropical humid climates (continued) Af –Closest to the equator –Smallest annual range of temperature –6.9-10 inches of rain per month –Most thunderstorms in afternoon –Linked to ITCZ –Tropical rain forests Am –Seasonal onshore winds during summer monsoon –Climates with most yearly precipitation –Jungle vegetation

14. Class #31: Wednesday, November 10, 2010 14 Tropical moist climates (continued) Aw –Farthest A climate from the equator –Often border Af –Tropical wet and dry –Wet summers, dry, cooler winters –Linked to the seasonal migration of the ITCZ –Vegetation is savannah or tropical grasslands with scattered deciduous trees, as in the grasslands of Africa.

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16. Class #31: Wednesday, November 10, 2010 16 Dry (B) climates Potential evaporation minus precipitation <0 More land of this climate type than any other Lubbock has a B climate Descending branch of the Hadley circulation near the subtropical highs or Rain shadow of a mountain range

17. Class #31: Wednesday, November 10, 2010 17 Dry climate subtypes 2 nd letter –“S” for steppe or semi-arid (like Lubbock) –“W” for true desert (extremely dry) 3 rd letter –“h” for low-latitude, hot (yearly average temperature >= 64ºF) –“k” for mid latitude, cool (yearly average temperature <64ºF)

18. Class #31: Wednesday, November 10, 2010 18 Dry climate subtypes (continued) BWh Extremely dry and hot; can have large sand dunes; Sahara, Arabian peninsula, central Australia, most extreme B climate BSk Least extreme B climate; midlatitude steppe, often high plateau, Lubbock, Denver, San Diego; often rain shadow BSh Much of Mexico, lower latitude, subtropical steppe BWk Central Asia, very dry, midlatitude rain shadow, continental interior

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21. Class #31: Wednesday, November 10, 2010 21 C Climate type All C are moist, plentiful precipitation All C are midlatitudes Average temperature of coolest month between 27ºF and 65ºF Have many subtypes; Chapter 14 concentrates on a few 2 nd letter like A subtypes –“f” no dry season –“w” brief dry period in winter

22. Class #31: Wednesday, November 10, 2010 22 C Climate type (continued) 3 rd letter –“a” hot summer –“b” warm summer –“c” cool summer

23. Class #31: Wednesday, November 10, 2010 23 C Climate subtypes Cfb, Cfc Marine west coast –Northwest coast of US, Canada –Often cool ocean currents Cfa, Cwa Humid subtropical –Southeastern US –30-100 inches of rain per year Csa, Csb Mediterranean –Along a coast, mild winter –Greece –Dry summer, semi-permanent subtropical high

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27. Class #31: Wednesday, November 10, 2010 27 D Climate type Severe (winter) Midlatitude Similar to C but severely cold winter Average temperature of coldest month <27ºF Snow on ground for extended periods Average temperature of warmest month >50ºF Overall, large change in temperature with season

28. Class #31: Wednesday, November 10, 2010 28 D climate subtypes 2 nd letter –“f” no dry season –“w” winter dry season 3 rd letter –“a” hot summer –“b” warm summer –“c” cool summer –“d” extremely severe winter

29. Class #31: Wednesday, November 10, 2010 29 D Climate Subtypes (continued) Humid continental –Dfa, Dfb, Dwa, Dwb –Dfa, for example, Chicago Subarctic –Dfc, Dfd, Dwc, Dwd –Long winter –Brief cool summer

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33. Class #31: Wednesday, November 10, 2010 33 E climate type Polar climate, very dry and cold Poleward of Arctic/Antarctic Circle, latitude 66.5º E climate subtypes –ET Tundra: mosses, lichens, flowering plants, woody shrubs, small trees, permafrost –EF Ice caps: no vegetation; Greenland, Antarctic Plateau

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35. Class #31: Wednesday, November 10, 2010 35 H climate type: Highland Large variation of temperature and precipitation over small horizontal distances Large diurnal temperature variation Can be dry or moist, depending on orientation, humidity, and whether prevailing winds are upslope or downslope