1. The Physical Environment
Climate

2. Climate vs. Weather Climate—long-term average pattern of weather
--local, regional, or global
Weather—the combination of factors
--temperature
--humidity
--precipitation
--wind
--cloudiness
--atmospheric conditions

3. The greatest constraint
Availability of heat and water
Influences amount of solar energy that plants can capture
Controls distribution and abundance of plants and animals

4. I. Solar radiation
A. The earth is covered with solar radiation as photons.
--51% reaches surface of earth
--most of this % is converted back to heat warming the atmosphere
--small % used in photosynthesis
--this radiation causes thermal patterns

6. B. Thermal patterns + earth’s rotation + movement around sun =
prevailing winds and ocean currents
These winds and ocean currents influence distribution of rainfall.

7. II. Greenhouse effect
Intercepted solar radiation varies with latitude—2 influencing factors
The radiation hits earth’s surface at a greater angle, spreading over a larger area
Also traveling through more atmosphere, or a deeper layer of air

8. Tilt of earth is 23.5o with respect to sun
—results in seasonal variation in temperature and length of day
1. Spring (vernal) equinox
2. Fall (autumnal) equinox
3. Summer solstice—June 22nd
4. Winter solstice—December 22nd

9. III. Seasonality of solar radiation
Temperature variation /day length increases with latitude
Arctic and Antarctic –day length varies from 0-24 hours

10. Variations in solar radiation
Explain latitudinal changes
Seasonal changes
Daily changes in temperature
BUT, do not explain why temperature gets colder with altitude…

11. BUT, do not explain why temperature gets colder with altitude…

12. As air reaches a higher altitude it becomes less dense—
Adiabatic cooling—results from the fewer collisions of the air molecules
--the rate of temperature change with elevation is called adiabatic lapse rate

13. IV. Circulation of air masses
Air masses circulate globally
Warmest air at equator
Moves north and south toward poles
Cools, becomes heavier
Sinks over Arctic/Antarctic regions
Then flows toward equator —replacing warm air

14. V. Rotation of earth East-west rotation of earth
Deflects pattern of air
Causes Coriolis force/effect
Causes right deflection in N. hemisphere
Including air masses
Causes left deflection in S. hemisphere

15. Wind flows Prevailing winds formed by Coriolis force
Series of belts of prevailing winds
Polar regions—Polar easterlies
Equator region—Easterly trade winds
Middle latitudes—Westerlies
Doldrums— low pressure around equator

16. Wind patterns Initiate surface flow in oceans
Each ocean dominated by 2 great circular water motions—gyres
Northern hemisphere— clockwise currents
Southern hemisphere— counterclockwise current

17. VI. Temperature/moisture
Influences amount of moisture air can hold
Warm air holds more moisture than cold air
Amount of water vapor held in a volume of air = saturation vapor pressure
Amount of water expressed as percentage of saturation vapor pressure = relative humidity
Temperature which saturation vapor pressure is dew point temperature

18. VII. Global patterns Precipitation exhibits a global pattern
Temperature, wind and ocean currents determine global pattern of precipitation
Westerly winds move across tropical oceans—gather moisture
Warm air cools as it rises—dew point reached
Clouds form—precipitation falls

19. Annual world precipitation

20. VII. Global patterns con’t
Winds move northward and southward—cooling
Cool air descends
2 belts of dry climate encircle the world
Descending air warms/holds more moisture
Draws water from the surface of earth

21. VIII. Microclimates
A. Small areas where environmental conditions are different
Organisms find their niche in microclimates
Vegetation can reduce ground temperature 7-12oC
Heavy grass cover can reduce wind at ground level

22. Common microclimates North facing slopes South facing slopes
Exhibit one type of microclimate
South facing slopes
Exhibit another microclimate

23. C. Mountainous topography
Influences local/regional microclimates
Changes patterns of precipitation
Intercepts air flow
Air mass reaches mountains-ascends-cools-becomes saturated
Releases moisture on windward side
Cool, dry air descends other side—picks up moisture from land

24. Phenomenon is called rain shadow
Found at continental divide
Found on Hawaiian Islands