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Dynamic Earth

Dynamic Earth. Earth's Atmosphere. Thin Gaseous envelope. The atmosphere is a thin layer of air that protects the Earth’s surface from extreme temperatures and harmful sun rays. Figure 1.2. Composition of Atmosphere (Mixture of gases, solids, and liquids).

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Dynamic Earth

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  1. Dynamic Earth

  2. Earth's Atmosphere Thin Gaseous envelope The atmosphere is a thin layer of air that protects the Earth’s surface from extreme temperatures and harmful sun rays Figure 1.2

  3. Composition of Atmosphere(Mixture of gases, solids, and liquids) • Early atmosphere was much different than today • Volcanoes produced nitrogen and carbon dioxide, but little oxygen • More than 2 billion years ago, early organisms began producing oxygen • Eventually, oxygen formed an ozone layer that protected Earth from harmful rays • Green plants and diverse life forms developed

  4. Atmospheric Gases(Mixture of gases, solids, and liquids) • Nitrogen - 78% • Oxygen - 21% • Water Vapor – 0 to 4% • Used for clouds and precipitation • Carbon Dioxide - .037% • Keeps Earth warm and is used by plants to make food • Argon - .93% • Traces of neon, helium, methane, krypton, xenon, hydrogen, and ozone

  5. Atmospheric Gases(Mixture of gases, solids, and liquids) • Atmosphere is changing with the introduction of pollutants; increasing human energy use is increasing the amount of carbon dioxide • Pollutants mix with oxygen and other chemicals to form smog • Aerosols include solids such as dust, salt, and pollen • Liquids include water droplets and droplets from volcanoes

  6. Five Layers of the Atmosphere

  7. Lower Layers of Atmosphere • Troposphere: lowest layer – extends up to 10km; contains 99% of the water vapor and 75% of the atmospheric gases • The troposphere is the first layer above the surface and contains most clouds and half of the Earth's atmosphere. • Weather occurs in this layer. • Most of the layer’s heat is from Earth • Temperature cools about 6.5 degrees Celsius per kilometer of altitude.

  8. Lower Layers of Atmosphere • Stratosphere – directly above troposphere, extending from 10 km to about 50 km above Earth’s surface • Portion of the upper layer contains high levels of a gas called ozone • Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.

  9. Upper Layers of Atmosphere • Mesosphere – extends from the top of the stratosphere to about 85 km above Earth • Coldest layer with little ozone • Meteors or rock fragments burn up in the mesosphere. • Ionosphere here – layer of charged particles

  10. Upper Layers of Atmosphere • Thermosphere – thickest atmospheric layer found between 85 km and 500 km above Earth’s surface • The thermosphere is a layer with auroras, known for its high temperatures. • Warms as it filters out X-rays and gamma rays from the Sun • Ionosphere here, too – help carry radio waves.

  11. Upper Layers of Atmosphere • Exosphere - The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere. • Outer layer where space shuttle orbits.

  12. Layers of Atmosphere

  13. Atmospheric Pressure • Molecules closer to the surface are more densely packed (at higher pressure) together than those higher in the atmosphere because of the mass of gases pressing down on them from higher in the atmosphere

  14. Temperature in atmospheric layers • The troposphere is warmed primarily by the Earth’s surface; temperature decreases as altitude increases in this layer. • Temperatures increase as altitude increases in the stratosphere, particularly in the upper portion – ozone • Temperatures decrease with altitude in the mesosphere • Thermosphere and exosphere are the first to receive Sun’s rays, so they are very hot

  15. The Ozone Layer • About 19 km to 48 km above Earth in the stratosphere (90%) and troposphere (10%). • Layer of 3-atom molecules that protects the Earth from the Sun’s harmful ultraviolet radiation • Life depends on the ozone! • Pollutants called chlorofluorocarbons (CFCs) have harmed the ozone • CFCs were used in refrigerators, air conditioners, aerosol sprays, and foam packaging ~ if products leak, CFCs enter atmosphere • Ozone layers has a large hole over Antarctica and a smaller one over the North Pole

  16. Ozone Hole

  17. Solar Energy • Some of the Sun’s energy coming through Earth’s atmosphere is reflected or absorbed by gases and/or clouds in the atmosphere.

  18. Solar energy Greenhouse Effect • Solar energy that is absorbed by the Earth’s land and water is changed to heat that moves/radiates back into the atmosphere (troposphere) where gases absorb the heat, a process known as the greenhouse effect.

  19. Greenhouse Animation

  20. Global Warming • Effects of Global Warming on Wildlife • Global Warming VIDEO • Global Warming VIDEO #2

  21. Heat • Energy that flows from an object with a higher temperature to an object with a lower temperature • Heat is transferred through the atmosphere by: • Radiation:energy that is transferred in the form of rays or waves • Conduction:energy that is transferred by direct contact • Convection:energy that is transferred by currents • Molecules move closer together, making air more dense, and air pressure increases • Cold air sinks, pushing up warm air, which then cools and sinks, pushing up more warm air

  22. Water Cycle – water makes up 70% of Earth’s surface!!

  23. Water Cycle Video Link • The HYDROSPHERE includes all of the water at or near the Earth’s surface • Water moves back and forth between Earth’s atmosphere and surface • Energy from the sun causes water to evaporate from the hydrosphere and rise as vapor • Sun provides water cycle’s energy • Water on the surface absorbs heat and evaporates, entering the atmosphere • Condensation – water vapor changes back into liquid • Clouds of water become heavy and water falls to Earth as precipitation • The cycle repeats itself continuously

  24. Air Pollution • When harmful substances build up in the air to unhealthy levels, the result is air pollution • Most is the result of human activities, but can also come from natural sources, such as volcanic eruptions, dust, pollen, spores • May be solids, liquids, or gases • Primary pollutants are put directly into the air (smoke). • Secondary pollutants form when primary pollutants react with other substances in the air. An example of this is ground-level ozone, formed from car emissions reacting with oxygen in the air.

  25. History • Clean Air Act – 1970, 1990 • Gave EPA the authority to regulate vehicle emissions • EPA required the gradual elimination of lead from gasoline, resulting in a 90% reduction in lead pollution • Catalytic converters in automobiles clean exhaust gases before the pollutants are released into the atmosphere • Cars and trucks produce 95% fewer emissions than they did 30 years ago

  26. History (cont’d) • California Zero-Emissions Vehicles (ZEV) Program • Encourages the development of less polluting vehicles • Has also been adopted in NY, ME, MA, VT • Battery-powered vehicles are the only real ZEV’s • Partial ZEV’s include Hybrids and Methanol Fuel Cell cars

  27. Industrial Air Pollution • Most industrial pollution comes from burning of fossil fuels – including electrical generating plants • Produces SO2, NOx • Others, including dry cleaners, oil refineries, chemical manufacturers produce VOCs (chemicals that produce toxic fumes) • Clean Air Act requires the use of pollution-control devices, like scrubbers, which removes pollutants by spraying them with water

  28. Sources of Primary Air Pollutants • Household products • Power plants • Motor vehicles • All responsible for emitting 1 or more of the following • Carbon monoxide (CO) • Nitrogen oxide (NO) • Sulfur dioxide(SO2) • Volatile organic compounds (VOCs).

  29. Sources of Primary Air Pollutants – Particulate Matter • Fine particles • enter air from fuel burned by vehicles & coal-burning power plants • Coarse particles • cement plants, mining operations, incinerators, wood-burning fireplaces, fields, & roads

  30. Sources of Primary Air Pollutants • Nitrogen oxide • Vehicles & coal-burning power plants • Sulfur dioxide • Power plants, refineries, and metal smelters • Human-made emissions of VOCs • Vehicles and gas stations

  31. Temperature Inversions • Air circulation usually keeps air pollution at a safe level • When a temperature inversion occurs (warmer air above cooler air), it traps the pollutants nearer to the surface of the Earth. • This is more common in cities located in valleys, like LA

  32. Indoor Air Pollution

  33. Sick-Building Syndrome • Occurs in buildings with poor air quality • Most common in hot places that are tightly sealed to keep out the heat • Fixed by finding and removing the source of pollution • Fixed by improving air ventilation

  34. Sources of Indoor Air Pollution

  35. Effects of Air Pollution • Short Term • headache; nausea; irritation to the eyes, nose and throat; coughing; tightness in the chest; and upper respiratory problems, worsens asthma • Long-Term • emphysema, lung cancer, and heart disease.

  36. Light & Noise Pollution • Light pollution does not pose a health risk • Diminishes view of night sky • Wastes energy • Include billboards and other signs lit from below • Noise pollution may cause temporary or permanent hearing loss

  37. What is Acid? • 0 – 6.9 = acidic • 7.1 – 14 = basic • 7 = neutral • Pure water is 7 • Human pH is between 7.35 – 7.45 • Natural Rainfall is acidic • (between 5.0 – 5.6) • Why? • Naturally occurring CO2 + H20  Carbonic Acid

  38. Acid Precipitation • Caused by oxides released into the air combining with water to form sulfuric and nitric acids • Acid rain has a pH of less than 5.0. Normal precipitation has a pH of about 5.6 • The precipitation flows into lakes and rivers, and into the soil • Causes harm to local crops, animals • Causes the pH of the soil to drop, thereby dissolving nutrients normally found in the soil and making the nutrients unavailable to plants • Clogs the openings on the surface of plant leaves

  39. Acid Deposition • Any substance in the atmosphere that produces a pH lower than natural rainfall (5.0) • Wet – rain, snow, sleet, hail, clouds, fog, dew, frost • Dry – gases or small particles

  40. Natural Acid Rain Sources • Desert soils • Windblown dust from alkaline soils can raise pH • Nitric • Lightning • Sulfuric • Hot springs • Volcanoes • Decaying organic matter

  41. Man-Made Acid Rain Sources • Fossil fuel combustion from coal, fuel oil, gas • Sulfuric Acid • Canada: metal smelters • US: power plants • Nitric Acid • Motor vehicle exhaust

  42. Man-Made Acid Rain Sources • Midwest & Ohio River Valley • Highest concentration of power plants & industry in US • PA • Directly downwind from Midwest & Ohio River Valley • 1 of largest polluters of acid rain chemicals • Record for most acidic average annual rainfall

  43. Midwest/Northeast Controversy • Tall Stacks • Smokestacks built higher to carry pollutants farther away from source • Tracers • Chemicals not normally found in atmosphere are carried w/pollutants

  44. Midwest/Northeast Controversy • Captex Experiment • (Cross Appalachian Tracer Experiment) • Plotted the path of tracers in pollutants • Data indicated movement of various pollutants • 50% of sulfate emissions in Canada are from US

  45. Ecosystems • Organisms tolerate certain pH ranges • Humans? • Brook trout < 5.0 • Brown trout > 5.5 • Rainbow trout ≥ 6.5 • Salamanders require 7.0 for egg development • Water < 4.3 = fishless

  46. Ecosystems • pH < 6.0 affects many fish • Can’t reproduce • Fewer eggs • Undeveloped • Young underdeveloped

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