earths atmosphere

• Oxygen in the atmosphere

  Approximately 21%
• Nitrogen in the atmosphere

  Approximately 78%
• Evidence for the early atmosphere is limited because humans were not around to experience it
• Early atmosphere development


  1. Volcanoes released carbon dioxide and water vapour

  2. As the Earth cooled, the water vapour condensed to form rivers, lakes and oceans

  3. Life evolved in the water. Photosynthetic organisms took in carbon dioxide and released oxygen

  4. Carbon became 'locked up' in sedimentary rocks and fossil fuels which decreased the amount of carbon dioxide in the atmosphere

  5. Nitrogen was released from the volcanoes. It is very unreactive and so has gradually built up in the atmosphere over time
• Source of oxygen in the atmosphere

  Photosynthesising organisms such as algae
• Decrease in atmospheric carbon dioxide

  1. Formation of sedimentary rocks (after carbon dioxide dissolved in the sea)

  2. Formation of fossil fuels
• Greenhouse gas


  A gas in the atmosphere that absorbs infrared radiation, thus heating up the atmosphere
• Greenhouse gases


  • Carbon dioxide
  • Methane
  • Water vapour
• Greenhouse effect


  Short wavelength radiation comes to Earth from the sun in the form of light. It is absorbed by the Earth's surface which radiates long wavelength radiation in the form of infrared radiation. This long wavelength radiation is absorbed by the greenhouse gases in the atmosphere, causing the atmosphere to warm up
• Human activities that increase methane

  • Growing rice
  • Keeping cattle
• Human activities that increase carbon dioxide

  • Burning fossil fuels
  • Deforestation
• Global climate change


  The long term changes in the climate due to global warming
• Information in the media about global climate change may be biased because it is very hard for Scientists to model, which leads to opinions being displayed in the media
• Major cause of climate change

  Global warming
• Potential effects of global climate change

  • Melting ice caps - leading to flooding and loss of habitat
  • More extreme weather events
  • Changes to or loss of habitats
  • Changes in the amount or timing of rainfall
• Carbon footprint


  A measure of the amounts of greenhouse gases released by a product, service or event
• Reducing carbon footprint


  1. Using renewable energy sources instead of fossil fuels

  2. Using efficient processes that cut waste

  3. Governments could tax companies that emit a lot of greenhouse gases

  4. Using public transport or walking
• Limitations of actions to reduce carbon footprint

  • Work still to be done on alternative technologies that result in lower carbon dioxide emissions
  • Governments are worried that changes will impact the economic growth of communities
  • Not all countries are on board
  • Individuals need to make changes too and lack of education may prevent this
• Atmospheric pollutants


  Burning fossil fuels
• Elements in fuels that can lead to atmospheric pollution

  Carbon, hydrogen and sometimes sulphur
• Gases released into the atmosphere when a fuel is burnt

  • Carbon dioxide
  • Carbon monoxide
  • Water vapour
  • Sulphur dioxide
  • Oxides of nitrogen
• Particulates


  Solid particles and unburned hydrocarbons
• Formation of carbon monoxide when fuels are burnt

  During the incomplete combustion of fossil fuels (when they are burnt in a limited supply of oxygen)
• Formation of soot when fuels are burnt

  During the incomplete combustion of fossil fuels (when they are burnt in a limited supply of oxygen)
• Formation of sulphur dioxide when fuels are burnt

  When fossil fuels contain sulphur impurities and are burnt, the sulphur reacts with the oxygen in the air to form sulphur dioxide
• Formation of oxides of nitrogen when fuels are burnt


  When nitrogen and oxygen in the air react due to the heat created when burning fossil fuels (ie in an engine)
• Carbon monoxide


  A compound made from one carbon and one oxygen atom, CO
• Properties of carbon monoxide


  • No colour, no smell
• Problems caused by carbon monoxide

  Binds with the red blood cells in a body and prevents them from carrying oxygen which can lead to fainting, coma or death
• Problems caused by sulphur dioxide and oxides of nitrogen

  When they mix with clouds they form sulphuric acid or nitric acid which then falls as acid rain. Acid rain kills plants and damages buildings it can also cause respiratory problems in humans if it is breathed in.
• Problems caused by particulates

  They can lead to global dimming and cause respiratory problems if breathed in.