C9 - Atmosphere

C9 - Atmosphere

1. Evolution of atmosphere

   • Phase 1 - volcanoes gave out gases
     • Early atmosphere mostly carbon dioxide, virtually no oxygen
       • Like Mars and Venus
     • Some nitrogen, water vapour, small amounts of ammonia and methane
     • Phase 2 - oceans, algae and green plants absorbed CO_2
       • Water vapour condensed into oceans
         • Carbon dioxide dissolved in oceans, formed sediments on seabed
       • Algae and green plants absorbed carbon dioxide so they could do photosynthesis
       • Crude oil and natural gas formed from deposits of plankton
       • Coal is sedimentary rock made from thick plant deposits
       • Phase 3 - green plants and algae produced oxygen
         • Photosynthesis
         • Algae evolved first then green plants
         • As oxygen built up, more complex life evolved
         • 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

2. Greenhouse gases/ climate change

   • Methane, carbon dioxide and water vapour act like insulating layer
   • Don't absorb short wavelength radiation, do absorb long wavelength and re-radiate it, back towards earth
   • Polar ice caps could melt, rise in sea levels
   • Changes in rainfall pattern

3. Carbon footprints

   • Measure of amount of carbon dioxide and greenhouse gases released over full life cycle of something
   • Reducing
     • Renewable sources used instead of fossil fuels
     • Using more efficient processes
     • Tax based on amount of greenhouse gases things emit
     • Cap on emissions
     • Technology that captures CO_2 before it gets released
   • Difficult because some don't want to reduce

4. Air Pollution

   • Carbon dioxide and water vapour released in complete combustion
   • Incomplete combustion, particulates of carbon and unburnt fuel are released and carbon monoxide
     • Particulates get stuck in lungs, respiratory problems
     • Global dimming, reflection of sunlight back into space
     • Carbon monoxide dangerous and stops blood transporting oxygen
   • Sulphur dioxide and nitrogen oxides cause acid rain
     • Kills plants, damages buildings, corrodes metals, causes respiratory problems