Weather and Climate

1. Weather and Climate

2. Air Temperature • Variation • Latitude • Seasonal solar energy input • Elevation • Topography

5. Types of Precipitation • Orographic • Frontal • Convective

6. Orographic Precipitation • Wind forces air up and over mountains • Rain on windward side • Desert on leeward side: Rain shadow • Examples • Cascades & Sierras • Rockies, Andes

8. Frontal Precipitation • Air forced up a boundary between cold and warm air masses • Air masses • Region of air with similar characteristics • Cold front • Cold air mass moves towards warm air mass • Typical weather • Warm front • Warm air mass moves towards cooler air mass • Typical weather

11. Convective Precipitation • Warm, humid rises, expanding and cooling • Saturation point is reached • Clouds form • Adiabatic cooling • Decrease in temperature that results from expansion of rising air

13. Global Circulation • 4 zones • Intertropical convergence zone (ITCZ) • Convectional precipitation • Trade winds • Subtropical high-pressure zones • Areas of dry, bright sunshine, little precipitation • Midlatitude low-pressure zones • Westerly winds, Polar front • Polar high-pressure zones • Dense air, high pressure • Little precipitation

16. Ocean Circulation Patterns • Wind creates waves and currents • Gyres • Wind-driven circular flows • El Niño • Occasional shifts in ocean circulation

18. Storms • Midlatitude Cyclones • Hurricanes and typhoons • Tropical cyclones • Need warm, moist air • Storm surge • Monsoons • Tornadoes

19. Classifying Climate • Allows analysis and planning • Communication • Köppen System • Distribution of plants • 5 basic climate types with subdivisions • Most widely used system

20. Climate Regions • Horizontal bands based on latitude • Climate regions similar to • Bioregions • Temperature and precipitation maps • Other influences • Continents • Mountains

22. Humid Low-Latitude Tropical Climates (A) • Warm all year • Humid tropical (Af, Am) • +/- 10 degrees N/S of equator • Warm & humid; Little seasonal temp. variation • High temps; Rain • Amazon River Basin, Equatorial Africa, Islands of South East Asia • Seasonally humid tropical climates (Aw) • Concentrated rainfall • Seasonal shifts of ITCZ • Central & South America

23. Dry Climates (B) • Dry climates, BW & BS • 35% of Earth’s land area • Border low latitude humid climates on North and South • North Africa, Central Asia • Desert climates (BWh, BWk) • Warm and dry • Subtropics • New Mexico (BWh), China (BWk) • Semi-arid climates (BSh, BSk) • Transitional areas between deserts and humid areas • Grasslands, steppes • Seasonal temperature contrasts

24. Warm Mid-latitude Climates (C) • Seasonal temp variation • Less precipitation • Humid subtropical (Cfa, Cw) • Latitude: 25-40 degrees on east side of continents • Eastern China, SE US, Brazil, Argentina • Marine west coast (Cfb, Cfc) • Continental west coasts, 35-65 degrees • Mild climates • California to coastal Alaska, Southern Chile • Mediterranean climates (Cs) • Dry summers with seasonal precipitation

25. Cold Mid-latitude Climates (D) • Humid continental climates (Dfa, Dwa, Dfb, Dwb) • Strong contrasts • Remote from oceans = little moisture • Interior & eastern side of Northern Hemisphere Continents (35-60 degrees) • Subarctic climates (Dfc, Dwc, Dfd, Dwd) • Northern edge of humid continental climates • No agriculture • Northern Hemisphere only • Vegetation: Boreal forests

26. Polar Climates (E) • High latitude climates • Low temps • Extreme seasonal variability • Tundra climate (ET) • Permafrost • Tundra • Ice-cap climates (EF) • Near poles & high altitudes at low latitudes

31. Climate Change • 3 hypotheses • Astronomical • Geometry of Earth’s orbit • Sunspots • Geologic • Continental drift • Volcanic eruptions • Human • Atmosphere • Vegetation