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Topic 6: Atmospheric Systems and Societies

6.1 Introduction to the Atmosphere
Significant Ideas:
  • The atmosphere is a dynamic system that is essential to life on Earth.
  • The behaviour, structure and composition of the atmosphere influence variations in all ecosystems.
Knowledge & Understanding:
  • The atmosphere is a dynamic system (with inputs, outputs, flows and storages) that has undergone changes throughout geological time.
  • The atmosphere is predominantly a mixture of nitrogen and oxygen, with smaller amounts of carbon dioxide, argon, water vapour and other trace gases.
  • Human activities impact atmospheric composition through altering inputs and outputs of the system. Changes in the concentrations of atmospheric gases—such as ozone, carbon dioxide, and water vapour—have significant effects on ecosystems.
  • Most reactions connected to living systems occur in the inner layers of the atmosphere, which are the troposphere (0–10 km above sea level) and the stratosphere (10–50 km above sea level).
  • Most clouds form in the troposphere and play an important role in the albedo effect of the planet.
  • The greenhouse effect of the atmosphere is a natural and necessary phenomenon maintaining suitable temperatures for living systems.
Application & Skills
  • Discuss the role of the albedo effect from clouds in regulating global average temperature.
  • Outline the role of the greenhouse effect in regulating temperature on Earth.
Energy in the Atmosphere
6.1 Intro to Atmosphere
Interactive Atmosphere Design Lab
6.2 Stratospheric Ozone
Significant Ideas:
  • Stratospheric ozone is a key component of the atmospheric system because it protects living systems from the negative effects of ultraviolet radiation from the Sun.
  • Human activities have disturbed the dynamic equilibrium of stratospheric ozone formation.
  • Pollution management strategies are being employed to conserve stratospheric ozone.
Knowledge & Understanding:
  • Some ultraviolet radiation from the Sun is absorbed by stratospheric ozone causing the ozone molecule to break apart. Under normal conditions the ozone molecule will reform. This ozone destruction and reformation is an example of a dynamic equilibrium.
  • Ozone depleting substances (including halogenated organic gases such as chlorofluorocarbons—CFCs) are used in aerosols, gas-blown plastics, pesticides, flame retardants and refrigerants. Halogen atoms (such as chlorine) from these pollutants increase destruction of ozone in a repetitive cycle, allowing more ultraviolet radiation to reach the Earth.
  • Ultraviolet radiation reaching the surface of the Earth damages human living tissues, increasing the incidence of cataracts, mutation during cell division, skin cancer and other subsequent effects on health.
  • The effects of increased ultraviolet radiation on biological productivity include damage to photosynthetic organisms, especially phytoplankton, which form the basis of aquatic food webs.
  • Pollution management may be achieved by reducing the manufacture and release of ozone-depleting substances. Methods for this reduction include: recycling refrigerants, and developing alternatives to gas-blown plastics, halogenated pesticides, propellants and aerosols developing non-propellant alternatives.
  • UNEP has had a key role in providing information, and creating and evaluating international agreements, for the protection of stratospheric ozone.
  • An illegal market for ozone-depleting substances persists and requires consistent monitoring.
  • The Montreal Protocol on Substances that Deplete the Ozone Layer (1987) and subsequent updates is an international agreement for the reduction of use of ozone-depleting substances signed under the direction of UNEP. National governments complying with the agreement made national laws and regulations to decrease the consumption and production of halogenated organic gases such as chlorofluorocarbons (CFCs).
Application & Skills
  • Evaluate the role of national and international organizations in reducing the emissions of ozone-depleting substances.
Systems: YouTube Video Lesson
Systems & Models PPT
6.3 Photochemical Smog
Significant Ideas:
  • The combustion of fossil fuels produces primary pollutants that may generate secondary pollutants and lead to photochemical smog, the levels of which can vary by topography, population density and climate.
  • Photochemical smog has significant impacts on societies and living systems.
  • Photochemical smog can be reduced by decreasing human reliance on fossil fuels.
Knowledge & Understanding:
  • Primary pollutants from the combustion of fossil fuels include carbon monoxide, carbon dioxide, black carbon or soot, unburned hydrocarbons, oxides of nitrogen, and oxides of sulfur.
  • In the presence of sunlight, secondary pollutants are formed when primary pollutants undergo a variety of reactions with other chemicals already present in the atmosphere.
  • Tropospheric ozone is an example of a secondary pollutant, formed when oxygen molecules react with oxygen atoms that are released from nitrogen dioxide in the presence of sunlight.
  • Tropospheric ozone is highly reactive and damages plants (crops and forests), irritates eyes, creates respiratory illnesses and damages fabrics and rubber materials. Smog is a complex mixture of primary and secondary pollutants, of which tropospheric ozone is the main pollutant.
  • The frequency and severity of smog in an area depends on local topography, climate, population density, and fossil fuel use.
  • Thermal inversions occur due to a lack of air movement when a layer of dense, cool air is trapped beneath a layer of less dense, warm air. This causes concentrations of air pollutants to build up near the ground instead of being dissipated by “normal” air movements.
  • Deforestation and burning may also contribute to smog.
  • Economic losses caused by urban air pollution can be significant.
  • Pollution management strategies include:
    • altering human activity to consume less fossil fuels—example activities include the purchase of energy-efficient technologies, the use of public or shared transit, and walking or cycling
    • regulating and reducing pollutants at the point of emission through government regulation or taxation
    • using catalytic converters to clean the exhaust of primary pollutants from car exhaust
    • regulating fuel quality by governments
    • adopting clean-up measures such as reforestation, regreening, and conservation of areas to sequester carbon dioxide.
Application & Skills
  • Evaluate pollution management strategies for reducing photochemical smog.
Systems: YouTube Video Lesson
Systems & Models PPT
6.4 Acid Deposition
Significant Ideas:
  • Acid deposition can impact living systems and the built environment.
  • The pollution management of acid deposition often involves cross-border issues.
Knowledge & Understanding:
  • The combustion of fossil fuels produces sulfur dioxide and oxides of nitrogen as primary pollutants. These gases may be converted into secondary pollutants of dry deposition (such as ash and dry particles) or wet deposition (such as rain and snow).
  • The possible effects of acid deposition on soil, water and living organisms include: direct effect—for example, acid on aquatic organisms and coniferous forests, indirect toxic effect—for example, increased solubility of metal (such as aluminium ions) on fish, and indirect nutrient effect—for example, leaching of plant nutrients.
  • The impacts of acid deposition may be limited to areas downwind of major industrial regions but these areas may not be in the same country as the source of emissions.
  • Pollution management strategies for acid deposition could include: altering human activity—for example, through reducing use, or using alternatives to, fossil fuels; international agreements and national governments may work to reduce pollutant production through lobbying and regulating and monitoring the release of pollutants—for example, through the use of scrubbers or catalytic converters that may remove sulfur dioxide and oxides of nitrogen from coal-burning powerplants and cars.
  • Clean-up and restoration measures may include spreading ground limestone in acidified lakes or recolonization of damaged systems—but the scope of these measures is limited.
Application & Skills
  • Evaluate pollution management strategies for acid deposition
Systems: YouTube Video Lesson
Systems & Models PPT