1. What Causes Different Climates?
----- Meeting Notes (11/29/11 11:17) -----

2. Map of World Climates

3. The Significance of Climate and Biomes
What is the difference between climate and weather?
1. Climate: the average, long-term conditions in a particular region
2. Weather: the condition of the atmosphere at a certain time and place
3. BOTH are measured in terms of temperature, wind speed, humidity, cloudiness, precipitation and other variables.
What is a biome?
1. Biomes are areas that are similar in climate and other physical factors
2. These areas tend to develop similar communities of plants and animals.

4. Global Climate Controls
Latitude
Elevation
Topography
Water Bodies
Atmospheric Circulation
Vegetation

5. A. Latitude – As latitude increases, solar intensity decreases
1. Because the Earth tilts on its axis, and because the earth is spherical the Sun’s rays strike the Earth at different angles. a. as a result, different parts of Earth receive different amounts of solar radiation.
Notice in area 3, the given amount of light and heat is spread over a larger area, so energy is less concentrated 3 1

6. The tropics receive the most solar radiation because the sun’s rays strike almost directly. Temperatures in the tropics are warm year-round.
4. The temperate zones have moderate conditions.
5. The polar zones receive the least radiation because the suns rays strike at a very low angle. Temperatures in polar regions are usually cold.

7. B. Elevation Elevation is the height above sea level.
1. The higher the elevation, the colder the climate
On average, air temperature drops about 6.5ºC for every 1000 m of altitude.
2. Elevation also helps determine rainfall

8. 1. Climates often differ on either side of a mountain.
C. Topography
1. Climates often differ on either side of a mountain.
a. As air rises over a mountain, it cools. As it cools, it condenses, and releases moisture (rain). This is called the windward side.
b. As the dry air flows over the mountain, it descends and warms, usually producing deserts. This is called the leeward side.

9. Mountains
Windward Side
Leeward Side
Direction of Prevailing Winds

10. Deserts such as the Atacama in Chile are common on leeward sides of mountains.
The dry area is
Called a rain shadow and can extend for hundreds of km downwind of a mountain range

11. D. Water Bodies
1. Continental interiors have large yearly temperature ranges, coastal cities have smaller temperature ranges
example: the California coast vs. the interior of California
a. Land gains and loses heat much faster than water.
b. Water bodies can warm or cool the air above them.

12. Water Bodies (additional info)
1. Ocean currents can warm or cool the air above.
2. Ocean currents may be considerably warmer or colder than the normal air temperature for that latitude.

13. E. Atmospheric Circulation
1. Global winds distribute heat and moisture around the earth
a. Winds move warm air toward the poles and cool air toward the equator
b. There are three basic wind systems in each hemisphere: Easterlies, Westerlies and the Trade Winds

14. These belts shift seasonally as the earth spins on it’s axis and different latitudes receive direct sunlight.
In the Northern Hemisphere, belts shift northwards in the summer, and southwards in the winter.

15. Vegetation 1. Vegetation can affect both temp and rainfall patterns
a. Vegetation influences how much of the sun’s energy is absorbed and how quickly this energy is released, which affects the climate.
2. Plants release water vapor from their leaves into the surrounding air, influencing humidity.

16. F. Vegetation, (additional info)
3. Some plants release particles that promote the formation of clouds.
4. Large areas of vegetation mimic large bodies of water.

17. Application
Explain which of the six climate controls are primarily responsible for the climate in the following cities:
Patagonia, Chile
San Francisco, California
Denver, Colorado
Carson City, Nevada

18. The End