C9 - Atmosphere

Evolution of atmosphere
1. Phase 1 - volcanoes gave out gases
  1. Early atmosphere mostly carbon dioxide, virtually no oxygen
    1. Like Mars and Venus
  2. Some nitrogen, water vapour, small amounts of ammonia and methane
  3. Phase 2 - oceans, algae and green plants absorbed CO_2
    1. Water vapour condensed into oceans
      1. Carbon dioxide dissolved in oceans, formed sediments on seabed
    2. Algae and green plants absorbed carbon dioxide so they could do photosynthesis
    3. Crude oil and natural gas formed from deposits of plankton
    4. Coal is sedimentary rock made from thick plant deposits
    5. Phase 3 - green plants and algae produced oxygen
      1. Photosynthesis
      2. Algae evolved first then green plants
      3. As oxygen built up, more complex life evolved
      4. 200 million years ago, atmosphere reached composition similar to what it is today
        80% nitrogen, 20% oxygen, small amounts of carbon dioxide, water vapour and noble gases
Greenhouse gases/ climate change
1. Methane, carbon dioxide and water vapour act like insulating layer
2. Don't absorb short wavelength radiation, do absorb long wavelength and re-radiate it, back towards earth
3. Polar ice caps could melt, rise in sea levels
4. Changes in rainfall pattern
Carbon footprints
1. Measure of amount of carbon dioxide and greenhouse gases released over full life cycle of something
2. Reducing
  1. Renewable sources used instead of fossil fuels
  2. Using more efficient processes
  3. Tax based on amount of greenhouse gases things emit
  4. Cap on emissions
  5. Technology that captures CO_2 before it gets released
3. Difficult because some don't want to reduce
Air Pollution
1. Carbon dioxide and water vapour released in complete combustion
2. Incomplete combustion, particulates of carbon and unburnt fuel are released and carbon monoxide
  1. Particulates get stuck in lungs, respiratory problems
  2. Global dimming, reflection of sunlight back into space
  3. Carbon monoxide dangerous and stops blood transporting oxygen
3. Sulphur dioxide and nitrogen oxides cause acid rain
  1. Kills plants, damages buildings, corrodes metals, causes respiratory problems

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C9 - Atmosphere

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