015 Atmospheric Science & Air Pollution Ch 13

1. Environment & Ecology 015 Atmospheric Science & Air Pollution Ch 13

2. “Congestion Charging Program” in London Green Bld. 1952- air pollution killed 4,000

3. Reduced traffic • Traffic delays cut by 25% • Travel speed increased by 30% • Bus use increase by 40%

4. The atmosphere • Atmosphere: the thin layer of gases that surrounds Earth • Provides us with oxygen • Absorbs solar radiation and moderates climate • Burns up incoming meteors • Transports and recycles water and nutrients • 78% nitrogen gas, 21% oxygen gas, 1% other gases • Human activity is changing the amounts of some gases. • Carbon dioxide, methane, ozone • The atmosphere has several layers.

5. The first two layers of the atmosphere • Troposphere: bottommost layer; 11 km (7 mi) high • Air for breathing, weather • Temperature declines with altitude • Stratosphere: 11-50 km (7-31 mi) above sea level • Drier and less dense, with little vertical mixing • Temperature warms with altitude • Contains UV radiation-blocking ozone, 17-30 km (10-19 mi) above sea level

6. The atmosphere’s four layers

7. Solar energy causes air to circulate • Convective circulation • Weather • Climate

8. Vernal equinox March 21 Sun vertical at equator Northern Hemisphere Names Winter solstice Dec. 22 Sun vertical at 23.5oS Winter solstice Dec. 22 Sun vertical at 23.5oS Summer solstice June 21 Sun vertical at 23.5oN Autumnal equinox Sep. 23 Sun vertical at equator

9. Earth further from sun Earth closer to sun

10. Non-rotating Earth Convection cell model

11. Add rotation and add landmasses unequal heating and cooling of the Earth

12. Physical properties of the atmosphere: Density • Warm, low density air rises • Cool, high density air sinks • Creates circular- moving loop of air (convection cell)

13. Physical properties of the atmosphere: Water vapor • Cool air cannot hold much water vapor, so is typically dry • Warm air can hold more water vapor, so is typically moist • Water vapor decreases the density of air

14. Physical properties of the atmosphere: Pressure • A column of cool, dense air causes high pressure at the surface, which will lead to sinking air • A column of warm, less dense air causes low pressure at the surface, which will lead to rising air

15. 90o High pressure, dry climate 60o Low pressure, wet climate High pressure, dry climate 30o ITCZ intertropical convergence zone= doldrums Low pressure, wet climate 0o 30o 60o 90o

16. Idealized winds generated by pressure gradient and Coriolis Force.  • Actual wind patterns owing to land mass distribution..

17. Storms pose hazards Atmospheric conditions can create life-threatening storms. • Hurricanes: formed when winds rush into areas of low pressure where warm, moist tropical air is rising • Called cyclones or typhoons in the Southern Hemisphere • Tornadoes: formed when a mass of warm air meets cold air, setting a powerful convective current in motion • The spinning funnel of rising air has winds up to 500 km/hr (310 mph).

18. Hurricanes in Hawaii • Hurricane season- June 1 to November 30 • Hurricanes approach from both east and south • Hawaii rarely gets hit • Hawaii is subtropical

19. Hurricane Path in Hawaii

20. Hurricane Iniki 1992

21. Outdoor air pollution • Air pollutants: gases and particulate material added to the atmosphere • Can affect climate or harm people or other organisms • Air pollution: the release of air pollutants • Outdoor (ambient) air pollution: pollution outside • Has recently decreased due to government policy and improved technologies in developed countries • Developing countries and urban areas still have significant problems.

22. Natural sources pollute: dust storms • Terrestrial Sources. • Unsustainable farming and grazing, erosion and desertification • Volcanoes • Fires • Clearing forests for agriculture Kīlauea

23. Legislation addresses pollution • The Clean Air Act of 1970 • Provides funds for pollution-control research • Sets standards for air quality, limits on emissions • Allows citizens to sue parties violating the standards • Starting in 1995, businesses and utilities could buy, sell, or trade permits for pollutants. • Each year, the amount of allowable pollution decreases.

24. The EPA sets standards • The EPA and states focus on six criteria pollutants. • Criteria pollutants: pollutants judged to pose great threats to human health • Environmental Protection Agency (EPA) sets nationwide standards for pollutant emissions.

25. Three criteria pollutants • Carbon monoxide(CO) • Sulfur dioxide (SO2 ) • Nitrogen dioxide (NO2 )

26. Criteria pollutants: tropospheric ozone • Tropospheric ozone (O3): a colorless gas with a strong odor • A secondary pollutant created from interactions of sunlight, heat, nitrogen oxides, and volatile carbons • A major component of smog • Poses a health risk as a result of its instability • Most frequently exceeds the EPA standard

27. Criteria pollutants: particulate matter and lead Mexico City 1986 Mexico City 2014

28. Volatile organic compounds (VOCs): Carbon-containing chemicals emitted by vehicle engines and industrial processes that can react to produce ozone

29. Volatile organic compounds (VOCs):

30. Air pollution has decreased since 1970

31. Air pollution has decreased since 1970

32. Reasons for the decline in U.S. pollution • Cleaner burning fuels • Scrubbers • Phase out lead gas

33. The Clean Air Act • Addresses emissions of hazardous air pollutants • Toxic air pollutants: substances known to cause cancer, reproductive defects, or neurological, development, immune system, or respiratory problems • The Clean Air Act identifies 188 toxic pollutants. • Emissions decreased 35% between 1990 and 2002.

34. The Clean Air Act • Regulate air pollution & prevention • Ozone protection • Prevent significant deterioration of air quality • Regulate motor and aircraft vehicle emissions • Clean fuel vehicles • Permits

35. Burning fossil fuels produces industrial smog Coal factories in China

36. Photochemical (brown air) smog

37. Industrial smog Photochemical smog

38. Synthetic chemicals deplete stratospheric ozone • Ozone layer: ozone in the lower stratosphere • Blocks incoming damaging ultraviolet radiation • Chlorofluorocarbons (CFCs): chemicals that attack ozone • Releases chlorine atoms that split ozone

39. The hole in the ozone Oct. 1979 Sep. 2013

40. Size of the Antarctic ozone hole Average Area: millions sq km North America 30 20 Antarctica 10 0 2001 1979 Prediction: 50 years to return to 1980 size

41. The Montreal Protocol addressed ozone depletion • Montreal Protocol: 180 nations agreed to cut CFC production in half • Today, production and use of ozone-depleting chemicals has decreased 95%. • The ozone layer is beginning to recover. • Challenges still face us. • CFCs will remain in the stratosphere for a long time.

42. Acid deposition is another transboundary issue • Acidic deposition: the deposition of acid, or acid-forming pollutants, from the atmosphere onto Earth’s surface • Acid rain: precipitation of acid • Atmospheric deposition: the wet or dry deposition on land of pollutants

43. Sources of acid deposition • Originates from burning fossil fuels that release sulfur dioxide and nitrogen oxides • These compounds react with water to form sulfuric and nitric acids.

44. Effects of acid deposition • Nutrients are leached from topsoil. • Metal ions (aluminum, zinc, etc.) are converted into soluble forms that pollute water. • Damages agricultural crops • Affects surface water and kills fish • Widespread tree mortality • Erodes stone buildings, corrodes cars, erases writing on tombstones • New technologies such as scrubbers have helped, but deposition’s effects are worse than predicted.

45. Effects of acid deposition

46. pH of precipitation in the U.S. Many regions of acidification are downwind of major sources of pollution.

47. Developing nations and air pollution China Beijing Olympic Stadium

48. Indoor airpollution Indoor air contains higher concentrations of pollutants than outdoor air. 6,000 people die per day from indoor air pollution. The average U.S. citizen spends 90% of the time indoors. Exposed to synthetic materials that exude volatile chemicals

49. Indoor air pollution in the developing world Comes from burning wood, charcoal, dung, crop wastes Homes have little to no ventilation. Fuel burning pollution causes an estimated 1.6 million deaths per year. Soot and carbon monoxide

50. Indoor air pollution in the developed world Tobacco and radon are the most dangerous indoor pollutants in the developed world. 4800 chemicals identified