1. Climate and Climate Change
Unit 2: The Atmosphere

2. Weather v. Climate
Weather is the stage of the atmosphere at a particular place at a particular point in time
Climate is the long-term prevailing weather conditions at a particular place based upon data gathered
Example: Phoenix v. Seattle

3. Climate-determining Factors
Latitude
Atmospheric circulation patterns
Oceanic circulation patterns
Local geography, solar, and volcanic activity

4. Latitude
Distance measured from the equator North or South (in degrees)
Amount of solar energy received is dependent on latitude
Where is it greater?
Seasonality
High latitudes – sunlight hits
the earth at an oblique
angle
Hours of daylight vary
greatly
What is equator? Poles?

5. Climate-determining Factors
Latitude
Atmospheric circulation patterns
Oceanic circulation patterns
Local geography, solar, and volcanic activity

6. Atmospheric Circulation Patterns
Three important properties of air:
Cold air sinks (why?); compresses and warms
Warm air rises (expands and cools)
Warm air can hold more water vapor (so what happens when it cools?)
Wind – movement of air within an atmosphere
At the equator, cool air cannot sink because warm air is pushing it up.
Pushes cool air towards about 30 degrees N/S!
Poles are also very dry
As the air sinks, it becomes warmer creating very dry conditions (warm air causes evaporation at the surface)

7. Prevailing Winds Winds that blow predominantly in one direction
Because of the Coriolis effect (the earth is rotating), these winds do not blow directly north or south
To the right in the N Hemisphere, to the left in the southern hemisphere

8. Climate-determining Factors
Latitude
Atmospheric circulation patterns
Oceanic circulation patterns
Local geography, solar, and volcanic activity

9. Oceanic Circulation Patterns
Why do oceans have a great effect on climate (think PoWater)?
Movement of surface ocean currents is by winds and rotation of the Earth
El Nino – Southern Oscillation – periodic change in location of warm and cold water mases
Winds in the Western Pacific (near China) strengthen and push warm water East (towards the US)
Increase in rain in the U.S., and drought in Indonesia/Australia
Number of El Nino years are increasing!
La Nina is the opposite

10. Climate-determining Factors
Latitude
Atmospheric circulation patterns
Oceanic circulation patterns
Local geography, solar, and volcanic activity

11. Local Geography, Solar/Volcanic Activity
Temperatures fall about 6 degrees Celsius for every 1000m increase in elevation!
Precipitation is affected too! (Rain Shadow)
Solar maximum – sun emits an increased amount of UV radiation
Volcanic eruptions – release what?
Reacts with water vapor and dust which forms a haze cooling the temperature

12. Seasonal Changes in Climate
What causes seasons?
Angles at which the rays strike the earth changes as the earth moves around the sun
Why do our hemispheres have flipped seasons