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Earth’s Atmosphere

Earth’s Atmosphere . Chapter 3, Section 2 Describe the composition of the Earth’s atmosphere Describe the layers of the Earth’s atmosphere Explain 3 mechanisms of heat transfer in Earth’s atmosphere Explain the greenhouse effect. General Description of Atmosphere. Mixture of gases Nitrogen

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Earth’s Atmosphere

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  1. Earth’s Atmosphere Chapter 3, Section 2 Describe the composition of the Earth’s atmosphere Describe the layers of the Earth’s atmosphere Explain 3 mechanisms of heat transfer in Earth’s atmosphere Explain the greenhouse effect

  2. General Description of Atmosphere • Mixture of gases • Nitrogen • Oxygen • Carbon dioxide & others • Addition/removal results in change • Living organisms (plants & animals) • Volcanic eruptions • Vehicles/industries • Insulates Earth’s surface

  3. Composition of Earth’s Atmosphere • Gases • 78% Nitrogen • 21% Oxygen • 1% other (Ar, CO2, CH4, H2O) • Atmospheric Dust • Solid particles • Soil, salt, ash fro fire & volcanic eruptions • Particulate matter (combustion, skin, hair, clothing bits, pollen bacteria & viruses • Aerosols (tiny liquid droplets) • Creates air pressure • Due to gravitational pull • Greatest near Earth’s surface

  4. Earth’s Atmospheric Layers (Ionosphere)

  5. Earth’s Atmospheric Layers • Divided into 4 layers based on • Temperature changes • Pressure changes

  6. Location of Atmospheric Layers above Earth’s Surface

  7. Troposphere • Nearest Earth’s surface (up to 18 km) • Makes up 75% of Earth’s atmospheric mass • Densest layer • Temperature & pressure decrease with altitude • Except tropopause – very top of layer • Stable temperature – called “cold trap” • Wider at equator than poles • Location of weather occurrence • Uneven heating due to convection current & winds • Causes cloud formation (rising water vapor cooled) • Related to Greenhouse effect

  8. Stratosphere • 2nd layer above Earth’s surface (32 km thick, 18-50 km above surface) • Temperature increases with altitude • Contains ozone layer • Reduces UV radiation • Thinning in Europe, Asia, North America & Antarctica

  9. Mesosphere • 50-80 km above surface • Coldest layer • Temperature decreases with increase in altitude • -30°C (-130°F) • Slows, prevents meteors entering atmosphere

  10. Thermosphere • 80 – 1000 km above surface • Very hot temperatures (200-2000°C or 360-3600°F) • Ionization of gases • N2 & O2 absorb X-rays & gamma rays • Radiate light (auroras) • Reflect radio waves • Area where shuttles orbit

  11. Energy Transfer in the Atmosphere • Radiation • Electromagnetic waves – absorbed & converted to heat • Visible light, X-rays, UV, Gamma (from sun) • Conduction • Transfer by contact between different matter • Convection • Caused by temperature differences & changes in densities of materials • Occurs only in fluids • Creates currents

  12. Energy Transfer Diagram

  13. Atmospheric Energy • Reaches Earth as electromagnetic radiation • ½ entering atmosphere reaches surface • ½ absorbed or reflected by gases, clouds, dust • Oceans & land radiate energy back into atmosphere • Prevents overheating of Earth’s surface • Dark colors absorb more energy than lighter ones • More energy released by darker colors • Explains higher temperatures in cities than surrounding country sides

  14. Energy Movement in Atmosphere • Result of convection currents • Air heated by Earth’s surface & rises into atmosphere • Cools as it rises & becomes more dense & sinks • Continual process results in circular movement of air (currents) • Occurs in troposphere, resulting in weather occurrences (rain, wind, tornadoes, etc.)

  15. Greenhouse Effect • Warming of Earth’s surface & lower atmosphere • Due to carbon dioxide, water vapor & other gases (methane, nitrous oxide) absorbing & radiating infrared waves • Called “greenhouse gases” • Maintain temperatures that support life • Excess amounts of carbon dioxide & methane result in increased heat retention • Caused by natural & industrial events • Cause abnormal increases in temperatures (heat) • Result in shifts in climatic zones, melting of polar ice caps, increased ocean levels around the world

  16. How is Earth’s atmosphere like glass in a car? • Both allow solar energy to pass through • Both can absorb and stop heat from escaping

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