Atmosphere and Climate Change Chapter 13

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

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

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.

Climate and Climate Change

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

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.

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.

Climate and Climate Change

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

Climate and Climate Change

Climate and Climate Change

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

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 20-30 year period CFC’s make there way to the upper atmosphere.

The Ozone Shield

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

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

The Ozone Shield

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

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

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)

Global Warming

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.

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

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)

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

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