The Atmosphere

1. The Atmosphere • Troposphere • Stratosphere • Mesosphere • Thermosphere

2. Troposphere • Has 75% of mass of earth’s air • Consists of 99% dry air, main two gases are nitrogen and oxygen. • Also holds water vapor. • Pressure decreases with altitude because average density decreases with altitude. • Temperature abruptly rises at top.

3. Stratosphere • Atmosphere’s second layer Ozone in this layer. • Volume of water vapor is less and volume of ozone is greater than in troposphere. • Our health depends on having enough ozone in stratosphere and little in troposphere.

4. Greenhouse effect • Happens in troposphere • Traps heat near earth’s surface • Water, carbon dioxide, and methane involved • Human inputs include carbon dioxide, methane, CFC’s, nitrous oxide. • What results if global warming

5. Air pollution • Presence of one or more chemicals in the atmosphere in quantities and duration that cause harm to human,s other forms of life, and materials.

6. Primary pollutants • Products of natural event, dust storms, volcanic eruptions, human activities like emissions from cars and smokestacks. • Can combine to form secondary pollutants

7. 2 – SO4 NO3 – Primary Pollutants CO2 CO Secondary Pollutants SO2 NO NO2 SO3 H2SO4 Most suspended particles HNO3 O3 H2O2 PANs Most hydrocarbons Most and salts Mobile Natural Stationary Sources

8. Sources of pollutants • Stationary sources – power plants and factories. • Mobile sources – cars and other mobile vehicles.

9. Photochemical smog • Mixture of primary and secondary pollutants formed under the influence of sunlight.

10. Industrial smog • Consists mostly of sulfur dioxide, suspended droplets of sulfuric acid, and a verity of suspended soil particles and droplets.

11. Temperature inversion/thermal inversion • When a layer of dense, cool air beneath can be trapped beneath a layer of less dense warm air in an urban basin or valley.

12. cool air Pollutants cool air warm air (inversion layer) warm air • surface heated by sun • warm air rises (incl. pollutants) • cools off, mixes with air of equal density & disperses • surface cools rapidly (night) • a layer of warm air overlays surface • polluted surface air rises but cannot disperse  remains trapped

13. What is Acid Deposition? • Acid Deposition is the falling of acids and acid forming compounds from the atmosphere to the earth’s surface. • Acid deposition is also known as acid rain.

14. Acid Deposition Continued… • Acidity of substances in water is pH • Numerical measures of the concentration of hydrogen ions in a solution • Solutions with pH less than 7 are acidic and those greater than 7 are alkaline or basic

15. Continued… • Natural precipitation is slightly acidic- pH of 5.0-5.6 • Primarily because of acid deposition, typical rain in the US is now about 10 times more acidic, with a pH of 4.3

16. What areas are affected by acid deposition? • It occurs on a rather regional rather than on a global basis. • Serious regional problems in areas downwind from coal burning power plants smelters, factories, and larger urban areas.

18. Affected Areas continued… • It is a growing problem in China, parts of the former Soviet Union, India, Nigeria, Brazil, Venezuela, and Columbia. • How seriously vegetation and aquatic life in lakes are affected depends mostly on whether its soils are acidic or basic.

19. What Are the Effects of Acid Deposition? • Risk analysis experts rate acid deposition as a medium risk to ecological problems and his risk to human health. • It has many harmful ecological effects. • Contributes to human respiratory diseases such as bronchitis and asthma.

20. Effects Continued… • It can damage statues, buildings, metals, and car finishes. • It can also damage tree foliage, and make it weaker and more susceptible to being damaged even more by other things.

21. Effects of Acid Deposition continued… • The areas hardest hit by acid deposition are mountaintop forests, which tend to have thin soils without much buffering capacity. • A combination of acid deposition and other air pollutants can make trees more susceptible to stresses such as cold temperatures, diseases, insects, drought, and fungi.

22. Continued… • Excess acidity can contaminate fish in some lakes with highly toxic methyl mercury.

23. How Serious is Acid Deposition in the US? • Numerous health studies have shown that the effects from exposure to the chemical components of acid deposition are a serious health problem and also damage materials.

24. Continued… • Many scientists support greatly reducing emissions from coal and oil burning facilities to reduce their harmful effects on human health and materials and to prevent acidic acidic compounds in soil and aquatic systems from exceeding the tolerance levels of various species and eventually serious and costly ecological and economic damage.

25. What Can Be Done to Reduce Acid Deposition? • Prevention Solutions: • Reducing energy use • Switching from coal to cleaner burning natural gas • Removing sulfur from coal before it is burned • Burning low sulfur coal • Removing SO2 particles, nitrogen oxide, and removing nitrogen oxides.

26. Types and Sources of Indoor Air Pollution • Higher in homes and commercial building than outdoors, as much as 70 times. • Pollution levels inside cars in traffic clogged urban areas can be up to 18 times higher. • At greater risks are smokers, infants, children under age 5, the old, the sick, pregnant people, people with heart problem.

28. Continued… • Pollutants found in building to be: dizziness, headaches, coughing, sneezing, nausea, burning eyes, chronic fatigue, and flu like symptoms, known as sick building syndrome. • New ones are more commonly “sick” than old ones because of reduced air exchange.

29. Continued… • Can be mineral fibers falling from ceiling tiles and blowing in from the lining of the air conditioning ducts. • Cigarette smoke, formaldehyde, asbestos, and radioactive radon are the most dangerous.

30. How human health is harmed? • Lung cancer • Asthma • Chronic bronchitis • Emphysema

31. What pollutants cause these problems? • Suspended particulate matter: asthma • Fine particles • Ultrafine particles • Sulfur dioxide: asthma/ bronchitis • Nitrogen oxides: asthma/ bronchitis • Volatile organic compounds: cancer

32. Humans Die from Pollution • Annually, U.S. estimates 65,000-200,000 premature deaths from outdoor pollution • Indoor pollution included: 150,000-350,000 premature deaths • Worldwide: 2.7 million premature deaths • Millions more face illness

33. Air Pollutants Damage Other Organisms • Aquatic Life: • Acid shock; kills fish • Plants: • Interferes with photosynthesis • Water loss • Susceptible to diseases

34. Laws Regarding Air Pollution • EPA established: • national ambient air quality standards (NAAQS) • National emission standards for toxic air pollutants • Clean Air Act of 1990

35. How Could Pollution Laws be Improved? • Focus on pollution prevention, rather than cleanup • Increase fuel efficiency standards • Require stricter emission standards for fine particulates • Reduce emissions of CO2 and other greenhouse gases

36. Reducing Outdoor Air Pollution Clean-up Methods: • Electrostatic precipitators • Baghouse filters • Cyclone separators • Wet scrubbers

37. Reducing Outdoor Air Pollution con. • Prevention Methods: • Burn low-sulfur coal • Remove sulfur from coal • Convert coal to a liquid or gaseous fuel • Shift to less polluting fuels

38. Reducing Indoor Air Pollutants • Using simple stoves that burn more efficiently (reduces deforestation) • Using simple solar cookers • Breathing wall • Absorbs indoor dirty air • Exhales clean air

39. How do we Protect the Atmosphere? • Focus more on pollution prevention • Improve energy efficiency • Slowing population growth • Regulating air quality for larger regions • Distribute cheap and efficient or solar cookstoves in developing countries

40. How do we Protect the Atmosphere? Con. • Reduce use of fossil fuels • Increase use of renewable energy • Integrate air-pollution, water-pollution, energy, and land-use policies • Phase in full-cost pricing, by taxing the production of air pollutants

41. Unit 7: Chapter 19 Ana Kaviani Ki Hong Lee Anne Penniall

42. Greenhouse effect • Certain gases in the atmosphere trap heat in the lower atmosphere (troposphere). • Mainly have to do with concentrations of heat-trapping or greenhouse gases and length of time they stay in the atmosphere.

43. Major greenhouse gases • Carbon dioxide • Chlorofluorocarbons (CFCs) • Methane • Nitrous oxide

45. Global warming • Have been caused by human activities: burning fossil fuels, agriculture, deforestation, and use of CFCs. • Developed countries account for about 60% of CO2 emissions and developing countries for 40%

47. Global warming (cont’d) • United States 23% of CO2 emissions • China 14% • Russia 7% • Japan 5%

49. Future of global warming and its effects • IPCC projects that temperature should rise 1-3.5 degrees C between 1990 to 2100 • Northern hemisphere should warm more and faster than the southern, because southern has more heat-absorbing ocean than land.

50. Ocean's affect on climate • Might amplify global warming by releasing more CO2 into the atmosphere or might dampen it by absorbing more heat. • Currently it keeps moderate troposphere temperature by removing 29% of Co2 excess.