Climatic Controls

1. Climatic Controls • Latitude • Altitude • Continentality • Prevailing Wind • Air Mass Variability • Topography • Ocean Currents • Land Use / Land Cover Change

2. Empiric classification: Köppen and later modified by Thornthwaite and Trewartha • looked at the global distribution of different plant and animal species and attempted to see how weather variables correlated with these patterns. • Temperature and precipitation

3. Köppen climate classification • Five primary categories • A Tropical • B Dry • C Mesothermal- “moderate” • D Microthermal- “low” • E Polar

4. BASIC WORLD CLIMATES

6. A climates • Mean temperature of coldest month is above 18°C (64°F) • Essentially, no freezes • Tropical Rainy: no dry season • Tropical Wet-and-Dry: short dry season • Tropical Monsoon: long dry season

7. TROPICAL RAINFOREST • Annual precip > 80” • No real seasons • Sticky, humid air, with little wind • High sun angle all year

8. Tropical Savanna and Monsoon • Savanna • alternating 3 month wet and dry periods dominated by movement of ITCZ • Monsoon • 5 - 7 month wet and dry regime • Both have 40 – 80” precip/year and average temps above 64°F every month

9. B climates • Arid and Semi-arid • P < PE • BW (Desert): • BS (Steppe):

10. Steppes • Dry short grass regions surrounding deserts • There are cold and hot steppes • Hot steppes are subtropical • South Texas • Cold steppes are at mid latitudes • Montana • Both have approximately 10 – 20” annual precip

11. Deserts • Hot and Cold deserts just like Steppes • Both have < 10” precip/year • Abundant sunshine • Hot desert • Sahara • Cold desert • Gobi

12. C climates • Essentially, it freezes but snow is not permanently on the ground in winter. • Mediterranean: dry summer • Wet-and-dry: dry winter • Humid: no dry season

13. Humid Subtropical • Mild winters with temperatures frequently dipping below freezing (northern limits) to infrequent freezes (southern limits) • Hot summers • Abundant precip throughout the year • SE U.S.

14. Mediterranean(dry summer subtropical) • No summer rain • Very little late spring/early fall rain • Cool moist winters and warm summers • Climate moderated by cold water • Abundant sunshine • Southern Cal

15. Marine West Coast • 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 • Seattle, London

16. D climates • Coldest month is less than -3°C; warmest month above 10°C. • Essentially, where snow remains on the ground for part of the winter. • Wet-and-dry: dry winter • Humid: no dry season

17. Humid Continental • Cold winters and warm summers • Precip in every month • Northern U.S. • Humid Continental (cool summers) • Located farther north with colder winters • Southern canada

18. Subarctic Boreal or Taiga • 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 • Most of Canada, Russia

19. E climates • Warmest month below 10°C. • Essentially, where it’s too cold for trees to grow • Tundra: it thaws in summer • Ice Cap: it doesn’t

20. Tundra and Icecap • 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

21. Alpine or Highland • Complex climates because of altitude • Can be a little of everything depending on the elevation

23. WORLD CLIMATES

25. ANNUAL PRECIP