Unit 3Unit 3

“Atmospheric Science & Air Pollution”

“Atmospheric Science & Air Pollution”

AtmosphereAtmosphere

• Atmosphere – thin layer of gases that surround the earth; composed of 5 sub layers– 1. Troposphere – closest to the earth, has most

oxygen of any of 5– 2. Stratosphere – Ozone predominantly found here– 3. Mesosphere – Ionosphere (weakly charged ions)

located in upper portion– 4. Thermosphere – increase in temperature;

uppermost portion of Ionosphere located here– 5. Exosphere – interface between earth’s atmosphere

and space; very few gases

AtmosphereAtmosphere

Atmospheric PropertiesAtmospheric Properties• Composition of gases: 78% N, 21% O, 1% trace

gases• As altitude increases, pressure ___________.

Why?• As altitude increases (exception in

thermosphere), temperature ____________. Why?

• As altitude increases, density ___________. Why?

• http://video.nationalgeographic.com/video/101-videos/weather-101-sci

Ozone LayerOzone Layer

• Found in the Stratosphere and is composed of O3 molecules

• Blocks UVA and UVB rays from reaching earth’s surface

• In the latter part of the 20th century, due to the use of products containing CFC’s, the Ozone Layer was depleted

• In the 1990’s many governments banned the use of CFC’s; as a result, the hole in the Ozone was reduced

Ozone Layer DepletionOzone Layer Depletion

• Keeping Ozone Layer intact is important because it keeps harmful UV rays from reaching the earth’s surface thereby preventing skin cancer

Weather and ClimateWeather and Climate

• Weather – day to day fluctuations in temperature and precipitation

• Climate – average weather conditions from year to year

• Whatever the conditions are in the atmosphere, those conditions will affect weather, and lastly climate

Air Masses and Pressure SystemsAir Masses and Pressure Systems

• Cold air mass = high pressure system• Warm air mass = low pressure system• As is the case with ocean currents, there are

horizontal and vertical air currents• Vertical air currents are called Convection

Currents (hot air or fluid expands and is therefore less dense than its cooler surroundings, thus it rises; as it cools it contracts, becomes more dense and sinks down creating something of a rolling motion)

Air Masses and Pressure SystemsAir Masses and Pressure Systems

• Also, the ocean’s physical conditions (temperature etc.) affect the physical conditions of the atmosphere and vice/versa

• Evidence of how the ocean’s physical conditions affect atmosphere/weather is the occurrence of hurricanes (require warm ocean water to develop)

• http://sciencelearn.org.nz/Contexts/H2O-On-the-Go/Sci-Media/Video/Water-and-weather

Air PollutantsAir Pollutants

• Primary Pollutants – emitted into the troposphere already in a form that is harmful to life in the biosphere– Example CFC’s

• Secondary Pollutants – result of primary pollutants reacting with each other or other substances in the atmosphere to form new pollutants– Example Acid Rain

Air PollutantsAir Pollutants

• Acid Rain – sulfur dioxide from coal burning power plants combines with water vapor

• Smog – coal and/or oil soot is released into the air

• Particulate pollution – small solid particles released into the air as a result of industrial processes; results in asthma and other respiratory ailments

Mitigating Air PollutantsMitigating Air Pollutants

• Just as the Clean Water Act was put in place to protect the hydrosphere, the Clean Air Act was put into effect beginning in the 1960’s to protect the atmosphere

• The Clean Air Act of 1990 - intent was to strengthen standards instituted in the 1970 version of the act; it also introduced an emissions trading program for sulfur dioxide (acid rain)

Market Based Incentives versus Government Regulations

Market Based Incentives versus Government Regulations

• Incentives = voluntary; if done properly provide an economic incentive to industry to “clean up their act”

• Regulations = involuntary; government requires industry to comply with regulations, sometimes causing them to become less competitive

• Which is better? It depends on the variables involved!