1. Climate and Climate Change

2. Weather vs. Climate
Weather – state of the atmosphere at a given time and place
Climate – long term prevailing weather conditions based on historical data

3. Factors that Determine Climate
Latitude
Distance North or South of the
equator (0o)
North Pole (90oN)
Low latitudes (near equator)
Solar energy concentrated on small area
Night/Day = ~12 hours
High latitudes (near poles)
Sun hits at an oblique angle – distributes solar energy over large area

5. Factors that Determine Climate
Atmospheric circulation
Cold, dense air sinks  compresses and warms
Warm, less dense air rises
Holds more water vapor than cold air
Clouds form when it cools (after rising)
Sun heats earth  warms air  it rises  replaced by cooler air
Wind

8. Factors that Determine Climate
Prevailing winds
Direction of wind throughout the year
Don’t move directly N or S
Deflected due to Earth’s rotation
To the right in northern hemisphere
Left in southern

10. Factors that Determine Climate
Oceanic Circulation Patterns
Ocean holds large amount of heat
Affected by wind and rotation of earth
Distribute warm/cold masses of water
Special circumstances
El Nino
La Nina

12. Southern Oscillation
Winds normally travel E  W in the tropical Pacific (trade winds)
From high pressure area in Eastern Pacific
To low pressure area in Western Pacific
3 to 8 years these pressure areas change
Reasons unknown
Winds travel in opposite direction (WE)
Southern Oscillation

19. Factors that Determine Climate
Topography
Mountains influence
precipitation
Rain shadow
Warm air forced to rise  cool  precipitation  dry air

20. Factors that Determine Climate
Seasonal changes
Tilt of Earth’s axis (23.5o)
Angle of sun’s energy changes
Summer – northern hemisphere tilted towards the sun
Receives direct sunlight

22. The Ozone Layer Ozone = O3 Ozone layer Absorbs most UV light from sun
Harmful to plants and animals
Natural sunscreen

23. Harmful Chemicals Chlorofluorocarbons (CFCs) Harmless, very stable
Coolant, spray cans
Break apart in upper
atmosphere
Cl atoms destroy O3
1 Cl can destroy
100,000 O3

24. Ozone Hole Thinning of stratosphere over Antarctica during the spring
Reported a few years after CFCs became widely used
Some areas are over 50% lost

26. Effects on Life
Loss of ozone layer  more UV light reaches earth  more mutations
Humans
Cancer
Weakened immune response
Marine life
Kills primary producers (less photosynthesis)
Land plats
Interferes with photosynthesis
Reduced crop yield

27. Can We Change It? Montreal Protocol (1987)
International agreement to protect ozone layer
US agreed to ban all substances that pose a significant danger by 2000
CFC production has decreased worldwide
CFCs remain active for years
Will take a long time to repair