Atmospheric Science and Air Pollution

1. Atmospheric Science and Air Pollution Chapter 17

2. Atmospheric Science Section One

3. The Atmosphere • Atmosphere: thin layer of gases that surround Earth • Purposes: • provides O2 • absorbs radiation • burns meteors • transports & recycles water and nutrients • moderates climate • Primary chemical Make-up: N2 (78%) O2 (21%) • Consists of four layers

4. Layers of the Atmosphere • Troposhere • Lowest, thinnest layer • Provides us with air • Responsible for weather patterns

5. Layers of the Atmosphere • Stratosphere • Second level • Contains ozone (O3), which shields against UV radiation

6. Layers of Atmosphere • Mesosphere • Second highest level • Thermosphere • Highest and largest level

7. Trends in the Layers • The higher the altitude, the less dense the gasses • The lower atmosphere is stable chemically, but the gases mix a lot; little mixing occurs above the troposphere

8. Thermal Inversion • Temperature decreases with altitude in troposphere and warm air rises. • Implication: air mixes as warm air rises where cooler air already exists • Thermal Inversion: situation in which cold air exists near ground below a band of warmer air • Implication: air does not mix and pollutants are trapped at low altitudes (where we live)

9. Small-Scale Air Circulation

10. Atmospheric Properties • Atmospheric Pressure: force per unit area produced by a column of air • Decreases with altitude • Relative Humidity: water vapor in volume of air: maximum amount water vapor air could hold • Varies from place to place • Temperature

11. Impacts of Solar Energy • Heats atmosphere • Helps create seasons • Causes air to circulate

12. Solar Energy Heats the Atmosphere

13. Solar Energy Helps Create Seasons

14. Solar Energy Causes Air to Circulate • Land and water radiate heat, causing air near the Earth’s surface to warm. • Warm air is less dense and rises, while cooler air is more dense and falls, creating a cycle (convective circulation)

15. Atmosphere Drives Weather • Weather: short-term atmospheric conditions • Climate: general, long-term atmospheric conditions in an area

16. Air Masses Interact to Produce Weather • Warm Front: mass of warmer, moister air approaches cooler, drier air • Results in light to moderate precipitation • Warm air slips above cooler air • Cold front: mass of cooler, drier air approaches warmer, moister air • Results in heavy precipitation • Cooler air pushes beneath warmer air

17. Cold Fronts and Warm Fronts

18. High and Low-Pressure Systems • High-Pressure System: air that moves away from center of high pressure as it descends • Results in fair weather • Low-Pressure System: air that moves toward center of low pressure as it ascends • Results in clouds and rain

19. Large-scale Circulation Systems • Convection Currents: circular rising and falling of air within certain latitude bands. • Global Wind Pattern: directional patterns within certain latitude bands

20. Convection Currents • Hadley Cells (0-30): warm air rises at 0, resulting in rain, and cools, sinking back down at 30 • Ferrel Cells (30-60): warm air rises near 60, resulting in rain, and sinks back near 30 • Polar Cells (60-90): warm air rises near 60, resulting in rain, and sinks back near 90

21. Global Wind Patterns

23. Air Pollution Section Two

24. Pollutant Categories • Primary Pollutant: pollutants that upon release are immediately harmful • Ex.: soot, CO • Secondary Pollutant: pollutants that must be “activated” by interacting with other chemicals to become harmful

25. Criteria Pollutants • CO (carbon monoxide) • SO2 (sulfur dioxide): damages plants, falls as acid rain • NO2 (nitrogen dioxide): damages plants, harms aquatic species, falls as acid rain • Tropospheric Ozone: damages plants • Particulate Matter: blocks sun, reducing photosynthesis rates • Lead: same affect on animals as humans

26. Other Pollutants • Volatile Organic Compounds: carbon containing chemicals that react with other compounds • Source: vehicles, household chemicals, industrial processes • Effect: produce bad ozone and secondary pollutants • Toxic Air Pollutants: pollutants that cause numerous serious health problems and ecological harm • Source: nature, smelting, sewage treatment, industrial processes • Effect: defects of all body systems • Chlorofluorocarbons (CFCs): • Source: man-made chemicals containing Cl, F, and C • Effect: deplete good ozone

27. CFC’s Deplete Ozone

28. Other Pollutants & Result of Pollution • Smog: mixture of unhealthy air pollutants • Industrial Smog/Haze: smog created by incomplete burning of coal or oil • Photochemical Smog: smog created by light driven reactions of primary pollutants with normal atmospheric compounds

29. Acid Deposition • Acid Deposition: release of acidic pollutants from atmosphere • Acid rain • Acid snow • Acid sleet • Acid hail • Acid: lower pH values (0pH - 6.9pH)

30. Natural Sources of Pollution

31. Dust Storms: Natural Polluters • Causes (natural and man-aided) • Winds sweeping over arid terrain • Winds sweeping over stripped farmland • Over 200 million tons of dust blown over distances greater than the distance between China and California. • Dust Bowl of 1930s

32. Volcanoes: Natural Polluters • Pollutants Produced • Particulate matter (millions on tons of ash) • Sulfur dioxide • Reacts with water and oxygen to produce aerosols, which reflect sunlight back into space

33. BrushFires: Natural Polltuers • Causes (natural and man-aided or created) • Dry, hot weather • Dry conditions with a spark created by man • Pollutants Produces • Particulate matter • CO • VOCs • 150 million + acres set ablaze/year

34. Legislation Addressing Air Pollution • Clean Air Act of 1970 • Set strict standards for air quality • Imposed emission limits • Provided research funds • Permits citizens to sue polluters • Clean Air Act of 1990 • Strengthened air quality standards • Created pollution permits • Montreal Protocol (treaty): signatories cut CFC production in half

35. Improvement of Air Quality

36. Air Pollution Trends in Other Countries

37. Solutions to Air Pollution • Catalytic converters • Pollution permit-trading program • Clean coal technologies • Electrostatic precipitators and scrubbers • Green cars and buildings

38. Catalytic Converters • Catalyze the conversion of toxic pollutants into non-toxic pollutants

39. Scrubber

40. Indoor Air Pollution • Indoor pollutants more concentrated than outdoor pollutants, thus air is generally more unhealthy indoors. • Sources of Indoor Air Pollution • Fuelwood burning • Tobacco smoke • Radon (a gas from Uranium decay) • Asbestos • VOCs • Living organisms (dust mites, dander, fungi, mold, etc.)