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Earth’s Atmosphere

Explore the composition and layers of Earth's atmosphere, including the mechanisms of heat transfer and the greenhouse effect. Learn about the different layers, energy transfer processes, and the impact of greenhouse gases.

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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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