Fall Lecture_1.ppt
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This document provides an overview of atmospheric chemistry and air pollution. It begins by describing the layers of the atmosphere and how solar energy and global wind patterns influence weather and climate. It then discusses various natural and human-caused sources of air pollution, including volcanoes, fires, dust storms, vehicles, factories, and coal burning. Several major air pollutants are explained in detail, along with the problems of smog and stratospheric ozone depletion. Solutions to reduce air pollution are also reviewed.
![© 2011 Pearson Education, Inc.
The first two layers of the atmosphere
• Troposphere = bottommost layer (11 km [7 miles])
- Air for breathing, weather
- The air gets colder with altitude
- Tropopause = limits mixing between troposphere
and the layer above it
• Stratosphere = 11–50 km (7–31 mi) above sea level
- Drier and less dense, with little vertical mixing
- Becomes warmer with altitude
- Contains UV radiation-blocking ozone, 17–30 km
(10–19 mi) above sea level](https://image.slidesharecdn.com/falllecture1-220927030018-cbdc5a33/85/Fall-Lecture_1-ppt-5-320.jpg)
Fall Lecture_1.ppt
- 1. © 2011 Pearson Education, Inc. Lecture 1 Atmospheric chemistry and air pollution
- 2. © 2011 Pearson Education, Inc. This lecture will help you understand: • The Earth’s atmosphere • Weather, climate, and atmospheric conditions • Outdoor pollution and solutions • Stratospheric ozone depletion • Acidic deposition and consequences • Indoor air pollution and solutions
- 3. © 2011 Pearson Education, Inc. The atmosphere • Atmosphere = the thin layer of gases around Earth - Provides oxygen - Absorbs radiation and moderates climate - Transports and recycles water and nutrients - 78% N2, 21% O2 • Minute concentrations of permanent (remain at stable concentrations) gases - Variable gases = varying concentrations across time and place • Human activity is changing the amount of some gases - CO2, methane (CH4), ozone (O3)
- 4. © 2011 Pearson Education, Inc. The atmosphere’s composition
- 5. © 2011 Pearson Education, Inc. The first two layers of the atmosphere • Troposphere = bottommost layer (11 km [7 miles]) - Air for breathing, weather - The air gets colder with altitude - Tropopause = limits mixing between troposphere and the layer above it • Stratosphere = 11–50 km (7–31 mi) above sea level - Drier and less dense, with little vertical mixing - Becomes warmer with altitude - Contains UV radiation-blocking ozone, 17–30 km (10–19 mi) above sea level
- 6. © 2011 Pearson Education, Inc. The two highest levels of the atmosphere • Mesosphere = 50–80 km (31–56 mi) above sea level - Extremely low air pressure - Temperatures decrease with altitude • Thermosphere = atmosphere’s top layer - Extends upward to 500 m (300 mi)
- 7. © 2011 Pearson Education, Inc. The atmosphere’s four layers • Atmospheric layers have different - Temperatures - Densities - Composition
- 8. © 2011 Pearson Education, Inc. Atmospheric properties • Atmospheric pressure = the force per unit area produced by a column of air • Relative humidity = the ratio of water vapor air contains to the amount it could contain at a given temperature - High humidity makes it feel hotter than it really is • Temperature = varies with location and time Atmospheric pressure decreases with altitude
- 9. © 2011 Pearson Education, Inc. Solar energy heats the atmosphere • The spatial relationship between the Earth and sun determines how much solar energy strikes the Earth • Microclimate = a localized pattern of weather conditions • Energy from the sun: - Heats and moves air - Creates seasons - Influences weather and climate • Solar radiation is highest near the equator
- 10. © 2011 Pearson Education, Inc. Solar energy creates seasons • Because the Earth is tilted, each hemisphere tilts toward the sun for half the year - Results in a change of seasons Equatorial regions are unaffected by this tilt, so days average 12 hours throughout the year
- 11. © 2011 Pearson Education, Inc. Solar energy causes air to circulate • Air near Earth’s surface is warm and moist • Convective circulation = less dense, warmer air rises - Creating vertical currents - Rising air expands and cools - Cool air descends and becomes denser - Replacing rising warm air Convection influences weather and climate
- 12. © 2011 Pearson Education, Inc. 2021 Kazakhstan cleanest city Chu , Zhambyl6 2021 Kazakhstan most polluted city Karagandy , Karaganda161
- 13. © 2011 Pearson Education, Inc. The atmosphere drives weather and climate • Weather and climate involve the physical properties of the troposphere - Temperature, pressure, humidity, cloudiness, wind • Weather = specifies atmospheric conditions over short time periods and within small geographic areas • Climate = patterns of atmospheric conditions across large geographic regions over long periods of time • Mark Twain said, “Climate is what we expect; weather is what we get”
- 14. © 2011 Pearson Education, Inc. Air masses produce weather • Front = the boundary between air masses that differ in temperature, moisture, and density • Warm front = boundary where warm, moist air replaces colder, drier air • Cold front = where colder, drier air displaces warmer, moister air Warm fronts produce light rain Cold fronts produce thunderstorms
- 15. © 2011 Pearson Education, Inc. Air masses have different pressures • High-pressure system = air that descends because it is cool - It spreads outward as it nears the ground - Brings fair weather • Low-pressure system = warm air rises and draws air inward toward the center of low pressure - Rising air expands and cools - It brings clouds and precipitation
- 16. © 2011 Pearson Education, Inc. Thermal (temperature) inversion • Thermal inversion = a layer of cool air occurs beneath warm air • Inversion layer = the band of air where temperature rises with altitude - Denser, cooler air at the bottom of the layer resists mixing • Inversions trap pollutants in cities surrounded by mountains • Air temperature decreases as altitude increases - Warm air rises, causing vertical mixing
- 17. © 2011 Pearson Education, Inc. Circulation systems produce climate patterns • Convective currents contribute to climatic patterns • Hadley cells = convective cells near the equator - Surface air warms, rises, and expands - Causing heavy rainfall near the equator - Giving rise to tropical rainforests • Currents heading north and south are dry - Giving rise to deserts at 30 degrees • Ferrel cells and polar cells = lift air and create precipitation at 60 degrees latitude north and south - Conditions at the poles are dry
- 18. © 2011 Pearson Education, Inc. Global wind patterns • Atmospheric cells interact with Earth’s rotation to produce global wind patterns - As Earth rotates, equatorial regions spin faster • Coriolis effect = the apparent north-south deflection of air currents of the convective cells - Results in curving global wind patterns called the doldrums, trade winds, and westerlies
- 19. © 2011 Pearson Education, Inc. Climate patterns and moisture distribution
- 20. © 2011 Pearson Education, Inc. Global wind patterns • Doldrums = a region near the equator with few winds • Trade winds = between the equator and 30 degrees - Blow from east to west - Weaken periodically, leading to El Niño conditions • Westerlies = from 30 to 60 degrees altitude - Blow from west to east • People used these winds to sail across the ocean • Wind and convective circulation in ocean water maintain ocean currents - And can create violent storms
- 21. © 2011 Pearson Education, Inc. Storms pose hazards • Atmospheric conditions can produce dangerous storms • Hurricanes = form when winds rush into areas of low pressure - Warm, moist air over the topical oceans rises • Typhoons (cyclones) = winds turn counterclockwise in the Northern Hemisphere - Drawing up huge amounts of water vapor - Which falls as heavy rains • Tornadoes = form when warm air meets cold air - Quickly rising warm air forms a powerful convective current (spinning funnel)
- 22. © 2011 Pearson Education, Inc. Hurricanes and tornadoes • Understanding how the atmosphere works helps us to: - Predict violent storms and protect people - Comprehend how pollution affects climate, ecosystems, and human health
- 23. © 2011 Pearson Education, Inc. 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 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
- 24. © 2011 Pearson Education, Inc. Natural sources pollute: volcanoes • Release particulate matter, sulfur dioxide, and other gases - Can remain for months or years • Aerosols = fine droplets of sulfur dioxide, water, oxygen - Reflect sunlight back to space - Cool the atmosphere and surface Volcanoes are one source of natural air pollution, as shown by the Mount Saint Helens eruption in 1980
- 25. © 2011 Pearson Education, Inc. Natural sources pollute: fires • Fires pollute the atmosphere with soot and gases • Over 60 million ha (150 million acres) of forests and grasslands burn per year • Human influence makes fires worse - Fuel buildup from fire suppression, development in fire-prone areas, “slash-and-burn” agriculture - Climate change will increase drought and fires In 1997, unprecedented forest fires sickened 20 million and caused a plane to crash
- 26. © 2011 Pearson Education, Inc. • Wind over arid land sends huge amounts of dust aloft - Even across oceans • Businesses, schools, and governments close • Unsustainable farming and grazing promote: - Erosion - Desertification Natural sources pollute: dust storms
- 27. © 2011 Pearson Education, Inc. We create outdoor air pollution • Air pollution comes from mobile or stationary sources • Point sources = specific spots where large quantities of pollutants are discharged (power plants and factories) • Non-point sources = more diffuse, consisting of many small sources (automobiles) • Primary pollutants = directly harmful and can react to form harmful substances (soot and carbon monoxide) • Secondary pollutants = form when primary pollutants interact or react with components of the atmosphere - Tropospheric ozone and sulfuric acid
- 28. © 2011 Pearson Education, Inc. Criteria pollutants: CO and SO2 • Carbon monoxide (CO) = colorless, odorless gas - Produced primarily by incomplete combustion of fuel - From vehicles and engines, industry, waste combustion, residential wood burning - Poses risk to humans and animals, even in small concentrations • Sulfur dioxide (SO2) = colorless gas with a strong odor - Coal emissions from electricity generation, industry - Can form acid precipitation
- 29. © 2011 Pearson Education, Inc. Criteria pollutants: NO2 • Nitrogen dioxide (NO2) = a highly reactive, foul- smelling reddish brown gas - Nitrogen oxides (NOx) = formed when nitrogen and oxygen react at high temperatures in engines - Vehicles, industrial combustion, electrical utilities - Contribute to smog and acid precipitation
- 30. © 2011 Pearson Education, Inc. Criteria pollutants: tropospheric ozone • Tropospheric ozone (O3) = a colorless gas with a strong odor - Results from interactions of sunlight, heat, nitrogen oxides, and volatile carbon-containing chemicals - A secondary pollutant - A major component of smog - Participates in reactions that harm tissues and cause respiratory problems - The pollutant that most frequently exceeds EPA standards
- 31. © 2011 Pearson Education, Inc. Criteria pollutants: particulate matter and lead • Particulate matter = suspended solid or liquid particles - Primary pollutants: dust and soot - Secondary pollutants: sulfates and nitrates - Damages respiratory tissue when inhaled - From dust and combustion processes • Lead = in gasoline and industrial metal smelting - Bioaccumulates and damages the nervous system - Banned in gasoline in developed, but not in developing, countries
- 32. © 2011 Pearson Education, Inc. Industrializing nations suffer increasing pollution • Outdoor pollution is getting worse in developing nations • Factories and power plants pollute - Governments emphasize economic growth, not pollution control • People burn traditional fuels (wood and charcoal) - And more own cars • China has the world’s worst air pollution - Coal burning, more cars, power plants, factories - Causing over 300,000 premature deaths/year
- 33. © 2011 Pearson Education, Inc. Pollution in developing nations is high More people own cars Smog in Beijing surrounds an Olympic stadium
- 34. © 2011 Pearson Education, Inc. Air pollution in China • The government is trying to decrease pollution - Shutting down heavily polluting factories and mines - Phasing out some subsidies for polluting industries - Installing pollution controls in factories - Encouraging renewable and nuclear energy - Mandating cleaner burning fuels • Air is improving in Beijing but not in other places • Asian (Atmospheric) Brown Cloud = a 2-mile-thick layer of pollution over southern Asia - Decreased plant productivity, increased flooding, etc.
- 35. © 2011 Pearson Education, Inc. Air quality is a rural issue, too • Airborne pesticides from farms • Industrial pollutants from cities, factories, and power plants • Feedlots, where cattle, hogs, or chickens are raised in dense concentrations - Voluminous amounts of dust, methane, hydrogen sulfide, and ammonia - Also create objectionable odors - People living or working nearby have high rates of respiratory illness
- 36. © 2011 Pearson Education, Inc. Smog: our most common air quality problem • Smog = an unhealthy mixture of air pollutants over urban areas • Sulfur in burned coal combines with oxygen to form sulfuric acid • Industrial (gray air) smog = industries burn coal or oil - Regulations in developed countries reduced smog • Coal-burning industrializing countries face health risks - Coal and lax pollution control Smog in Donora killed 21 people and sickened 6,000
- 37. © 2011 Pearson Education, Inc. Photochemical (brown air) smog • Produced by a series of reactions - Formed in hot, sunny cities surrounded by mountains • Light-driven reactions of primary pollutants and atmospheric compounds - Morning traffic releases NO and VOCs - Irritates eyes, noses, and throats • Los Angeles smog kills 3,900/year and costs $28 billion/year High levels of NO2 cause photochemical smog to form a brown haze over cities
- 38. © 2011 Pearson Education, Inc. Industrial smog Photochemical smog Creation of industrial and photochemical smog
- 39. © 2011 Pearson Education, Inc. We can reduce smog • Regulations require new cars to have catalytic converters • Require cleaner industrial facilities - Close those that can’t improve • Financial incentives to replace aging vehicles - Restricting driving • Vehicle inspection programs (“smog checks”) • Reduce sulfur in diesel; remove lead in gasoline • Electronic pollution indicator boards raise awareness • But increased population and cars can wipe out advances
- 40. © 2011 Pearson Education, Inc. Synthetic chemicals deplete stratospheric ozone • Ozone layer = ozone in the lower stratosphere - Blocks incoming ultraviolet (UV) radiation - Protecting life from radiation’s damaging effects • Ozone-depleting substances = human-made chemicals that destroy ozone by splitting its molecules apart • Halocarbons = human-made compounds made from hydrocarbons with added chlorine, bromine, or fluorine • Chlorofluorocarbons (CFCs) = a halocarbon used as refrigerants, in fire extinguishers, in aerosol cans, etc. - Releases chlorine atoms that split ozone
- 41. © 2011 Pearson Education, Inc. CFCs destroy ozone • CFCs are inert (don’t react) • CFCs remain in the stratosphere for a century • UV radiation breaks CFCs into chlorine and carbon atoms • The chlorine atom splits ozone • Ozone hole = decreased ozone levels over Antarctica One chlorine atom can destroy 100,000 ozone molecules
- 42. © 2011 Pearson Education, Inc. The Antarctic ozone hole • High-altitude polar stratospheric clouds form during the dark, frigid winter • Nitric acid in clouds splits chlorine off of CFCs - A polar vortex (swirling winds) traps chlorine - UV radiation in September (spring) sunshine dissipates the clouds and releases the chlorine - The chlorine destroys the ozone - December’s warmer air shuts down the polar vortex - Ozone-poor air diffuses, while ozone-rich air enters
- 43. © 2011 Pearson Education, Inc. The Montreal Protocol • Montreal Protocol = 196 nations agreed to cut CFC production in half by 1998 • Follow-up agreements deepened cuts, advanced timetables, and addressed other ozone-depleting chemicals - Industry shifted to safer, inexpensive, and efficient alternatives • Challenges still face us - CFCs will remain in the stratosphere for a long time - Nations can ask for exemptions to the ban
- 44. © 2011 Pearson Education, Inc. The Montreal Protocol is a success • It is considered our biggest environmental success story • Research developed rapidly, along with technology • Policymakers included industry in helping solve the problem • Implementation of the plan allowed an adaptive management strategy - Strategies responded to new scientific data, technological advances, and economic figures • The Montreal Protocol can serve as a model for international environmental cooperation
- 45. © 2011 Pearson Education, Inc. Protecting the ozone layer International agreements reduced ozone-depleting substances The hole in the ozone has stopped growing
- 46. © 2011 Pearson Education, Inc. Acid deposition • 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 containing acid - Rain, snow, sleet, hail • Atmospheric deposition = the wet or dry deposition on land of pollutants (mercury, nitrates, organochlorines) - From automobiles, electric utilities, industrial facilities
- 47. © 2011 Pearson Education, Inc. Burning fossil fuels produces acid rain • Burning fossil fuels releases sulfur dioxide and nitrogen oxides - These compounds react with water, oxygen, and oxidants to form sulfuric and nitric acids
- 48. © 2011 Pearson Education, Inc. Impacts of acid deposition • Nutrients are leached from topsoil • Soil chemistry is changed • Metal ions (aluminum, zinc, etc.) are converted into soluble forms that pollute water • Affects surface water and kills fish • Damages agricultural crops • Erodes stone buildings, corrodes cars, erases writing on tombstones
- 49. © 2011 Pearson Education, Inc. Sources of indoor air pollution
- 50. © 2011 Pearson Education, Inc. Living organisms can pollute indoors • Dust mites and animal dander worsen asthma • Fungi, mold, mildew, airborne bacteria cause allergies, asthma, other respiratory ailments, and diseases • Building-related illness = a sickness produced by indoor pollution • Sick building syndrome = a sickness produced by indoor pollution with general and nonspecific symptoms - Reduced by using low-toxicity building materials and good ventilation
- 51. © 2011 Pearson Education, Inc. We can reduce indoor air pollution • In developed countries: - Use low-toxicity materials, limit use of plastics and treated wood, monitor air quality, keep rooms clean - Provide adequate ventilation - Limit exposure to known toxicants - Test homes and offices and use CO detectors • In developing countries: - Dry wood before burning - Cook outside - Use less-polluting fuels (natural gas)
- 52. © 2011 Pearson Education, Inc. Conclusion • Indoor air pollution is a potentially serious health threat - We can significantly minimize risks • Outdoor air pollution has been addressed by government legislation and regulation in developed countries • Reduction in outdoor air pollution represents some of the greatest strides in environmental protection - There is still room for improvement, especially in developing countries
- 53. © 2011 Pearson Education, Inc. QUESTION: Review The major component of Earth’s atmosphere is: a) Nitrogen gas b) Oxygen gas c) Argon gas d) Water vapor
- 54. © 2011 Pearson Education, Inc. QUESTION: Review Ozone in the _________ is a pollutant, but in the ______ is vital for life. a) Stratosphere, troposphere b) Troposphere, stratosphere c) Troposphere, tropopause d) Stratosphere, thermosphere
- 55. © 2011 Pearson Education, Inc. QUESTION: Review With convective circulation: a) Less dense, cooler air rises b) Denser, warmer air rises c) Less dense, warmer air rises d) Denser, cooler air rises
- 56. © 2011 Pearson Education, Inc. QUESTION: Review If you were on a sailing ship going from the United States to Europe, you would want to be in the area of the _____. a) Doldrums b) Trade winds c) Westerlies d) Polar cell
- 57. © 2011 Pearson Education, Inc. QUESTION: Review The Clean Air Act does all of the following, EXCEPT: a) Forbid emissions trading b) Provide funds for pollution-control research c) Allow citizens to sue violators d) Set standards for air quality
- 58. © 2011 Pearson Education, Inc. QUESTION: Review Which criteria pollutant is highly reactive, foul smelling, and has a reddish brown color? a) Sulfur dioxide b) Nitrogen dioxide c) Tropospheric ozone d) Carbon monoxide
- 59. © 2011 Pearson Education, Inc. QUESTION: Review Why is the Montreal Protocol considered our greatest environmental success story? a) It has stopped global warming. b) It decreased criteria pollutants. c) It successfully stopped ozone depletion. d) It slowed acid deposition.
- 60. © 2011 Pearson Education, Inc. QUESTION: Viewpoints Think of a major city near you. Do you think drivers should have to pay to drive downtown? a) Yes, if mass transit is available. b) Yes, but only charge people who do not live in the downtown area. c) No, it’s my right to drive wherever I want to. d) I don’t care, because I don’t own a car.
- 61. © 2011 Pearson Education, Inc. QUESTION: Viewpoints Should the government be able to force industries to put pollution-control devices on their factories? a) Yes, I don’t want to be exposed to pollution. b) Yes, only if the people in the area agree. c) No, let the factory owner decide. d) No, in these tough economic times, we need to leave businesses alone.
- 62. © 2011 Pearson Education, Inc. QUESTION: Interpreting Graphs and Data What does this graph show about the stratosphere? a) It contains the most ozone. b) It is a very thin layer. c) Temperature decreases with increasing altitude. d) Temperature is not affected with increasing altitude.