1. Atmosphere and Climate Change
Chapter 13

2. Climate and Climate Change
Climate- long term prevailing weather conditions in a particular place
Factors that influence climate
Latitude
Atmospheric circulation patterns
Oceanic circulation patterns
Local geography
Solar activity
Volcanic activity

3. Climate and climate change
Latitude- distance north or south of the equator
Low latitudes- 12 hours of sun light, high temperatures year around, no seasons
High latitudes- sun light varies between summer and winter months, lower temperature than areas near the equator

4. Climate and Climate Change
Atmospheric circulation-
Cold air sinks
Warm air rises
Warm air holds more moisture than cold air
Sun light shines on the ground and warms the air above it. The warm air rises and cooler air moves in to fill its place. This causes wind.
The uneven heating of the earth’s surface and the spin of the earth causes prevailing winds.

5. Climate and Climate Change

6. Climate and Climate Change
Oceanic circulation patterns
Surface currents are mainly affected by prevailing winds
El Nino- short term (6-18 months), warm water is pushed east, causes increased rainfall in the southern US and central America, causes drought in Indonesia and Australia
La Nina- cooler than normal water- opposite effects to El Nino

7. Climate and Climate Change
Ocean Circulation Patterns
Pacific Decadal Oscillation- long term (20-30 year cycle), affects climate over North America, affects surface water temperatures, air temperatures, and precipitation patterns.

8. Climate and Climate Change
Topography-
Elevation- temperature drops 6 C for every 1000 ft
Mountains can affect precipitation
Sun
Solar maximum- increased amounts of UV radiation can increase stratospheric temperatures as well as lower atmospheric temperature.
Volcanic eruptions
Sulfur dioxide emitted from a volcano can reach the upper atmosphere and react with water vapor and dust to form a bright haze. This haze reflects sunlight back into space cooling the earth.

9. Climate and Climate Change

10. Climate and Climate Change
Seasonal Changes in Climate
Earth’s axis is tilted at 23.5
Summer = northern hemisphere leans toward the sun
Winter = southern hemisphere leans toward the sun

11. Climate and Climate Change

12. Climate and Climate Change

13. The Ozone Shield
Ozone layer- an area of the stratosphere where ozone is highly concentrated
Ozone = a molecule made of 3 oxygen atoms
Absorbs most of the UV light that reaches the earth from the sun

14. The Ozone Shield Ozone depletion-
Chlorofluorocarbons (CFC’s)- a class of human-made chemicals that might damage ozone
Nonpoisonous, nonflammable, non-corrosive
Used as..
coolant in refrigerators
To make foam
Spray propellant
Chemically stable at earth’s surface
Over a year period CFC’s make there way to the upper atmosphere.

15. The Ozone Shield

16. The Ozone Shield
Scientist have estimated that a single chlorine atom can destroy 100,000 ozone molecules.

17. The Ozone Shield
Thinning of the ozone layer was reported in 1985 (50-98%) around Antarctica.
Polar stratospheric clouds form causing CFC’s to breakdown to Cl. The Cl reacts with the ozone in the presence of UV light.
UV light kills living cells

18. The Ozone Shield

19. The Ozone Shield
1987 Montreal Protocol- a group of nations agreed to decrease the production of CFC’s
1992- developed nations agreed to ban the use and production of CFC’s

20. Global Warming
Greenhouse effect- process of heat absorption by gasses in the earths atmosphere
Greenhouse gases
Water vapor
Carbon dioxide
CFC’s
Methane
Nitrous oxide

21. Global Warming
Most scientist think that increased levels of greenhouse gases will cause increases in global atmospheric temperature, but not all scientist agree.
Global CO2 levels fluctuate throughout the year (high in winter and low in summer)

22. Global Warming

23. Global Warming
Some scientist believe that the warming trend that started at the beginning of the 20th century will continue. Other believe that the warming trend is part of a natural occurrence of fluctuating temperatures that appear throughout time.

24. Global Warming The Consequences Melting ice and rising sea level
Weather pattern changes
Stronger hurricanes and typhoons
Change in precipitation patterns
Human health problems
Heat related deaths
Increase in ground level ozone causing reparatory disease
Increase in disease carrying insects

25. Global Warming Consequences- con’t Agriculture
Droughts
Diseased crop yields may increase
Effects on plants and animals
Alter habitat ranges
Alter available food sources (zooplankton)

26. Global Warming Recent findings- IPCC Third Assessment Report
Average global temperature increased 0.6 C during 20th century
Snow cover and ice extent decreased
Global sea level has risen
Increase in greenhouse gases due to human activities

27. Global Warming Reducing Risk Kyoto Protocol (1997)
55% of nations ratify
Developed nations decrease emissions by 5% below their 1990 levels by 2012