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Weather and Climate Air Pollution issues Chapter 17 & 18 Weather – short-term atmospheric conditions. Climate – 30 year averages of atmospheric conditions. Temperature & Moisture most important considerations. Climate influences include: Latitude, Elevation, Topography (Orographic Lifting/Rain Shadow Effect), Vegetation, Distance from Ocean, Position on Continent. 6 Climate zones, subdivided into climate types. Zones are: Humid Equatorial; Dry; Humid Temperate; Humid Cold; Cold Polar; and Highland 3 Variations in Earth surface temperatures & climate are due to; Inclination of Earth’s axis in relation to the Sun and the Unequal Distribution of Land vs. Water & Differential Thermal Characteristics of Land & Water. Long-term changes may be due to variations in Solar activity & Earth orbit. Pp. 510 - 511 Lower angle of Sun’s rays hitting Earth = more surface area coverage/less concentration. Seasonal changes are largely due to Earth’s axial inclination in relation to the Sun. 4 Axial inclination – responsible for Seasonal Variations. 5 Atmosphere – Dry atmosphere composed of 78% Nitrogen (N2) & 21% Oxygen (O ). Remaining 1% composed of Argon, Carbon Dioxide, Neon, Helium, and other trace gases. Important atmospheric functions include shielding Earth’s surface from UV, X-rays, cosmic rays from space, while allowing visible and infrared wavelengths to penetrate atmosphere. Greenhouse Effect shields Earth from excessive diurnal temperature variations (day to night temperature variations). 6 Atmospheric Layers – Most important are Troposphere (surface to 11 miles) & Stratosphere (11 to 16 miles). Troposphere – “Weather maker”, turbulent, rich in water vapor/droplets. Stratosphere – “Ozone shield”, steady wind, but little turbulence. Ozone not present as a “layer”, but is more prevalent from 11 to 16 miles above Earth’s surface. Oxygen (O2) and Ozone (O3) both block UV radiation, but Ozone is more dense, more efficient, but is also unstable. Thinning seems seasonal, greatest in September. 7 Atmospheric Circulation – caused by: • Earth’s Rotation • Uneven Distribution of Land Mass • Properties of Heat Transfer between air/water/land • Solar Energy Horizontal/Latitudinal Wind “Belts” – Rossby Regime. • 00 to 300 North – Northeast Trade Winds • 300 to 600 North – Westerlies Wind Belt – Jet Stream • 600 to 900 North – Polar Easterlies 8 Vertical atmospheric circulation – Hadley cells – Driven by Equatorial Heating (Equatorial Low Pressure Zone). Pg. 479 Polar Cell Ferrel Cell Hadley Cell Low Pressure Zones = Rising Air, Counter-clockwise. High Pressure Zones = Falling Air, Clockwise. The vertical air movements of the Hadley Cells lead to: A persistent Low Pressure Zone at the Equator (00) A persistent Mid-Latitude High Pressure Zone at 300 A weaker, persistent Low Pressure Zone at 600 And a strong, persistent Polar High Pressure Zone at 900 called the Polar Vortex 10 The combined actions of the Horizontal Wind Belts, the Hadley Cells, & the Earth’s rotation lead to the Coriolis Effect, i.e., clockwise rotation of ocean currents in Northern Hemisphere. Example – Gulf Stream carries heat from sub-tropics northward, warms Scandinavia, British Isles. The North Pacific Drift carries enough heat to warm the NW coastline of North America. The wind-driven surface circulation patterns, called gyres, are influenced by landmass locations and coastline shapes. 11 Major Surface Ocean Currents 12 The varying density of sea water largely affects vertical ocean currents. Colder, saltier water tends to sink, while warmer, less salty water remains near the oceans surface. Pg. 511 Present-day circulation 13 There is evidence of past changes in the ocean “conveyor belt”, but all of the reasons are not known. Weakening of the North Atlantic – Gulf Stream component may bring about another ice age. El Niño – Southern Oscillation – periodic changes in wind/oceanic current patterns in Pacific Ocean. May be driven by solar activity. Under normal conditions – NE Trade Winds & SE Trade Winds combine to form E to W moving winds along InterTropical Convergence Zone across Pacific Ocean. Every 3 to 7 years, these winds weaken. 14 Under normal conditions – Convergence of Trade Winds push surface water to the west, causing an upwhelling of cold, organic-rich bottom water along the West Coast of South America. Under El Niño Pacific Ocean conditions – weakening of trade winds = weakening of South America upwhelling, affecting E. Pacific ecosystems & weather. El Niño/Southern Oscillation (pp. 510 – 511) Warm tropical waters in Western Pacific (Indonesia) generate a persistent low pressure system in the area. The Southern Oscillation refers to the alternating El Niño and La Niña events. A 12,000 yr history suggests faster oscillations during colder time periods. ENSO History Other research suggests ENSO and Atlantic Oscillations are driven by solar activity. 16 Global weather changes due to El Niño, may cause temperature spikes, e.g., 1998 El Niño. ENSO - Solar Activity Model La Niña – stronger trade winds 17 The Hydrologic Cycle is the dynamic movement of water through the atmosphere, over & below the land surface, through the life cycles of plants and animals, and to and from the oceans & other water bodies. Components: • Evaporation/Transpiration • Condensation • Precipitation • Runoff/Infiltration 18 El Niño wind currents are thought to interfere with Atlantic Hurricanes by preventing the vertical growth of cumulonimbus clouds in developing hurricanes. Why Does It Rain? Condensation of Water Vapor & Condensation Nuclei (minute particulates) needed Mechanisms for Atmospheric Uplift – •Cyclonic – Counter-clockwise rotation, uplift of air •Convection – Uplift by heat •Orographic Effect – Uplift by mountains Cooling Warming Remember – Low pressure – counterclockwise, rising air currents, convergence at surface. Most favorable for rain/snow. High pressure – clockwise, falling air currents, divergence at surface. Ocean Currents – Northern Hemisphere Earth’s Rotation and prevailing winds produce clockwise circulation in Northern Atlantic and Northern Pacific Oceans – Coriolis Effect. Example – Gulf Stream and Kuroshio Currents. In addition, there are drift currents and eddy currents that produce local current variations (next slide). Other factors influencing Oceanic Currents– •Fresh Water vs. Different Salinities •Differing Water Temperatures •Shape of Coastlines •Presence of Large Islands Other oceanic currents include vertical “upwhellings”, particularly along coastlines, that bring nutrient-rich bottom water to the surface and complex “thermohaline” currents, that may play a major role in global climate. 21 Ocean Currents Redistribute Heat North Pacific Summer North Pacific Winter North Pacific Summer Current Details North Pacific Winter Current Details North Atlantic Ocean North Atlantic Summer and North Atlantic Winter Seasonal Winds and Monsoons Best examples of Monsoon Season Rains occur with summer heating of large Asian landmass, generating intense convection that “draws” warm, moist air inland from the Indian Ocean. Orographic lifting caused by Himalayan Mts. results in flooding of Ganges River. Ganges Delta includes most of Bangladesh. Smaller continents may generate lesser “Monsoon” effects. CLIMATE CHANGE - The Sun provides the energy that drives the Earth’s climate. Variations in Solar activity and the Earth’s orbit affect primarily affect the climate. Compiled by R. S. Bradley and J. A. Eddy based on J. T. Houghton et al., Climate Change: The IPCC Assessment, Cambridge University Press, Cambridge, 1990 and published in EarthQuest, vol 5, no 1, 1991. Courtesy of Thomas Crowley. Ice core data over periods of 160,000 yrs. and 420,000 yrs. suggest a correlation between atmospheric CO2 and global temperatures. Disagreements between scientists focuses on the connection between CO2 and temperature. Which one leads and which one follows? Recent studies suggest that temperature leads by several hundred years or more. Human-Caused Global Climate Change Greenhouse heating first hypothesized by Svante Arrhenius (1896), concerns over effects of burning coal. In the larger scale – we have been undergoing global warming since the end of the last ice age (end of Pleistocene Epoch – 8,000 to 12,000 years ago). In the smaller scale – we have been undergoing global warming since the end of the Little Ice Age (1350 to 1850 AD). The Industrial Revolution began about 200 years ago. Mona Loa CO2 changes 1957 – 2002 = 315 ppm to 372 ppm 315 ppm = 0.0315% 372 ppm = 0.0372% 744 ppm = 0.0744% Evidence exists that increased CO2 = increased plant vitality = more photosynthesis = negative feedback loop. Kyoto objections Chirac: Kyoto "First Step Toward Global Governance“ Link to article Some believe the Kyoto Treaty is an attempt to plan the world’s energy use for the next century. This includes the use of taxes, rationing, and economic sanctions to punish “non-attainment”. Taxes and rationing will hurt economies of developed world, hinder Research & Development by Free Market. Other concerns: Loss of Sovereignty; Exemption of China, India, Brazil, and Mexico; Failure to include alternative scientific views; Over-reliance on models; Too much politics, etc… Remember – the UN is not elected. Compiled by R.S. Bradley and J.A. Eddy based on J.T. Houghton et al., Climate Change: The IPCC Assessment, Cambridge University Press, Cambridge, 1990 and published in EarthQuest, vo. 1, 1991. Courtesy of Thomas Crowley, Remembrance of Things Past: Greenhouse Lessons from the Geologic Record 1. (notice differences in time scales vs. previous diagram (slide 10). (Graph on right): Based on data from J. Imbrie, J.D. Hays, D.G. Martinson, A. McIntyre, A.C. Mix, J.J. Morley, N.G. Pisias, W.L. Prell, and N.J. Shackleton, in A. Berger, J. Imbrie, J. Hats, G. Kukla, and B. Saltzman, eds., Milankovitch and Climate, Dordrecht, Reidel, pp. 269-305, 1984.Courtesy of Thomas Crowley Global Warming: A Chilling Perspective 29 CLIMATE SKEPTICS Water Vapor Rules the Greenhouse –This is the one to study. Most-serious greenhouse gas is increasing Table 9.3 doesn’t even mention Water Vapor as a Greenhouse Gas Water Vapor vs. Carbon Dioxide as Greenhouse Gases Water Vapor in the Climate System Water Vapor as a Greenhouse Gas Carbon dioxide is a Greenhouse Gas and it is more efficient at trapping heat than water vapor/clouds, but the current amount is 385 ppm = 0.0385% Source: Prof. Richard Lindzen, Massachusetts Institute of Technology, U.S. Senate Hearing, May 6, 1992. 30 Convection Uplift Current Evidence of Climate Change Laundry list of predictions and problems blamed on Global Warming. “Around the world, coral reefs are bleaching because of higher water temperatures.” CLIMATE AND AIR POLLUTION U.S. releases 147 million metric tons of air pollutants (not including carbon dioxide or wind-blown soil). Since the 1970s, there has been progress in reductions of major pollutants, except Nitrogen oxides. Lack of progress noticeable, especially in southern Asia – “Asian Brown Cloud” – dust, smoke, dirt, volcanic ash, other particulates, rises above Asian cities and drifts southward over Indian Ocean after monsoon season, may be affecting ENSO system. Major Kinds of Pollutants Primary Pollutants – from the original source – volcanoes, motor vehicles, factory combustion, dust, open burning,… Secondary Pollutants – form from chemical reactions between primary pollutants. Chemical reactions may include photochemical reactions (triggered by sunlight) – Ground level ozone of most concern. Fugitive emissions – non-smokestack emissions – dust, soot and ash from open burning, hydrocarbons from pipelines, wells, refinery leaks, etc.. Conventional (criteria) pollutants – Sulfur dioxide, carbon monoxide, particulates, volatile organic compounds (VOCs), nitrogen oxides, ozone, and lead. 1970 Clean Air Act mandated EPA to monitor and limit concentrations of these pollutants within the ambient air (existing air conditions). Unconventional pollutants – less volume, greater toxicity than conventional pollutants, e.g., asbestos, benzene, mercury, PCBs, and vinyl chloride. Sources and Problems of Major Pollutants Sulfur dioxide – with water forms sulfurous acid. When oxidized to form sulfur trioxide with water turns to sulfuric acid. Hydrogen sulfide – Highly toxic in larger amounts, produces rotten egg odor assoc. with some oil wells and refineries, when combined with oxygen, also produces sulfuric acid. Nitrogen oxides – by-products of fuel combustion, some of which is from catalytic converters. Various nitrogen oxide gases are referred to as NOx gases. These are precursors of ground level ozone which combine with various hydrocarbons (VOCs) through photochemical reactions. Scotch pine trees can release nitrogen oxides when exposed to UV radiation. Carbon monoxide – product of incomplete combustion, combines with hemoglobin in blood, prevents absorption of oxygen. EPA Info - Carbon Monoxide May be a precursor of ground-level ozone. Particulate material – dust, ash, soot, lint, smoke, pollen, spores, algal cells, aerosols (minute droplets), asbestos,… Volatile Organic Compounds (VOCs) – organic gases, e.g., isoprenes (C5H8), terpenes (C10H15), and methane (CH4), oxidize to carbon monoxide and carbon dioxide. Brown air smog – combination of primary and secondary pollutants – most common to US cities. Gray air smog – results from burning of heavy, sulfur-rich fuel oil and coal. Formerly a problem in US cities, now more of a problem in some Eastern European and Asian cities. Metals – Pb, Zn, Ni, Hg, U. May be present in emissions from smelters, coal-burning power plants. Indoor air pollution – issues – outgassing from synthetic materials (formaldehyde, chloroform, benzene, styrene), rebreathing of cigarette smoke, dust mites, carpet fibers, mold, spores,… INTERACTION BETWEEN CLIMATE PROCESSES AND AIR POLLUTION Long range transport – China dust to Hawaii and western US, Sahara dust to Miami, industrial contaminants,… Stratospheric Ozone Depletion – Not a hole, but rather a thinning. Worst during Antarctic spring (September), recovers during Antarctic Summer (our Winter). The debates over: Are variations normal? How much of the chloride ion is coming from CFCs and how much from volcanoes? Chloride repeatedly cycles through the system, acting as a catalyst, possibly speeding up the breakdown of the already unstable ozone molecules. Tracking the Ozone Layer Good article – 16 pages long. April 2001 Report on Ozone Urban Climates – Inversions – usually triggered by rapid nighttime cooling in valleys or basins where air movement is restricted. Overlying warm layer w/out convection traps pollutants – El Paso, Mexico City, LA, Denver. Heat Island Effect – Concentration of heat within cities due to vehicles, factories, paving and building materials that absorb solar energy, lack of tree cover, buildup of dust, other particulates, concentration of ground-level ozone precursors. Asphalt, concrete, brick, etc. absorb solar energy – reradiate energy as infrared (heat). Trees provide cooling effect through evapotranspiration – emitting water vapor from their leaves. Evidence suggests that ground level ozone damages crops. Visibility loss in Blue Ridge Mts., Grand Canyon, elsewhere due to the migration of pollution from cities. Acid Deposition (acid rain) – results from the combination of rain and carbon dioxide, rain and nitrogen oxides, rain and sulfur gases. In dry climate, sulfate and nitrate particles can settle as particulates. Worst acid rainfall in areas associated with smelting of sulfide minerals (pyrite and related metallic ores). Sudbury, Ontario and Copperhill, Ga./Ducktown, Tenn. – examples. NAPAP – National Acid Precipitation Assessment Program – 10 year study (1980-1989), $537 million, almost 700 scientists, issued 28 volume report. Conclusion was that in most places in US, acid precipitation was a nuisance, not a crisis. EPA vs. Ed Krug Damage to Appalachian trees was due to aphids. Upstate New York lakes were acidic due to natural conditions. NAPAP study focused on United States, other nations with different fuels (more coal use, heavy fuel oils, less environmental regulations) may have more acid-rainfallrelated damage to buildings, forests, etc.. AIR POLLUTION CONTROL Past attempts at dilution and dispersion were only shortterm solutions to the problem. Most US air pollution is related to transportation and energy generation. Improvements in technology, fuel and fuel efficiency, and conservation are all viable strategies. Even though we have our problems – Re: the Eastern Bloc – “…a rigid bureaucracy, and lack of democracy have created ecological disasters. Where governments own, operate, and regulate industry, there are few checks and balances or incentives to clean up pollution.”