LECTURE 3 CH 4 VARIATIONS IN THE PHYSICAL ENVIRONMENT
pg. 73-81; 87-88; 95
MAJOR CONCEPTS
1) Global patterns in temperature and precipitation are established by energy of sun.
2) Uneven heating of the earth’s round surface and the tilt of earth on its axis combine to
produce predictable latitudinal variation in climate.
3) Uneven temperatures create winds; winds drive ocean currents that redistribute heat
and moisture.
4) Proximity to water and topographic/geologic features cause local variation in climate.
5) Biome existence and location have shifted through time.
Distribution of biomes is caused by variation in climate
Proximate causes of global variation in climate
*Overall model
Solar radiation  temperature  wind and ocean currents  precipitation
Features of earth contributing to climate variation
Temperature variation and its seasonality
Angle of solar radiation affects heat input
Latitudinal variation in temperature; hot at equator; cold at poles
Greater temperature range in N than S; land temp changes more easily than water
Seasonal change in location of solar equator  seasonal variation in temperature
Variation in temperature creates winds and winds affect ocean currents + direction
Wind  precipitation patterns
Hadley cells  variation in rain at 0 and 30 N and Spredictable locations of
tropical forests and deserts
ITCZ moves  seasonality in rainfall; brings dry seasons to tropics
Coreolis effect changes wind directionality from N and S to NE-SW and SE-NW
Ocean currents  variation in temperature and precipitation
N = clockwise; S = counterclockwise  affect whether bring warm or cold water
Cause upwellings and affect productivity in ocean
Cause shifts in biome location (deserts on W side of continents; temperate forests
rather than boreal forest in N. Europe)
Local effects on climate
Proximity to water; continental vs. maritine climates
Topography
Mountains  air cools as rises; cool air holds less moisture; it rains.
Change in biome with change in altitude
Changes in altitude parallel changes in latitude
Wind brings moisture from a certain direction;(from W in temperate latitudes)
Rain dumped on windward site rainshadow on leeward side
Biome differs on different sides of mountain
Orientation of mountain range (N- and S-facing slopes
different sun and microclimate (temp and soil moisture) 
different vegetation on different slopes
Causes of long-term temporal changes in biome distributions
Continental drift; continents at different latitudes
Mountain building  rainshadows arise
Milankovitch cycles bring changes in earth’s orbit, tilt, and wobble
Past climate change
Present climate change
Human alteration in land cover; forest recycle water locally