Earths atmposhere

• Atmosphere

  Gases held above the Earth's surface by gravity
• Proportion of gases in the atmosphere

  • About four-fifths (approximately 80%) nitrogen
  • About one-fifth (approximately 20%) oxygen
  • Small proportions (less than 1%) of other gases e.g. carbon dioxide, water vapour and methane
• Oxygen in the atmosphere

  • Essential for all living things to stay alive
  • Essential for the combustion (burning) of fuels
• Carbon dioxide


  A compound with the formula CO2
• Carbon is trapped in rocks and sediments, is found in organisms and in the ocean/atmosphere
• Carbon cycle


  Carbon dioxide is released and taken in from the environment
• Ways carbon enters the atmosphere

  • Respiration – all living organisms carry out respiration
  • Combustion – burning substances like fossil fuels releases carbon dioxide
  • Decomposition – when animals and plants die, microorganisms break down the organism which releases the carbon in the organisms into the atmosphere by respiration
• Photosynthesis


  Carbon dioxide + water glucose + oxygen
• Ways carbon is transferred

  • Animals feed on plants passing carbon from the plant to the animal
  • This is then exhaled as carbon dioxide during respiration
• Carbon sinks


  Absorb and store large amounts of carbon
• The plant and animal material may be fossilised over long periods of time and become fossil fuel for combustion
• Natural changes to the atmosphere

  • Volcanic activity (releases carbon dioxide)
  • Lightening (leads to oxides of nitrogen being produced)
• Man-made changes to the atmosphere

  • Burning of fossil fuels (releases carbon dioxide)
  • Deforestation (prevents carbon dioxide from being taken in)
  • Cattle farming and rice farming (release methane)
• Methane levels are increasing in the atmosphere as humans are doing more cattle farming and rice farming
• The carbon dioxide levels in the atmosphere are increasing due to human activity, specifically burning fossil fuels and deforestation
• Carbon footprint


  A measure of the amount of carbon dioxide released into the atmosphere as a result of the activities of a particular individual, organisation, or community
• Greenhouse gases


  • Water vapour
  • Carbon dioxide
  • Methane
• Greenhouse effect


  1. Radiation from the sun is emitted and passes through the atmosphere to the Earth's surface

  2. Some radiation is reflected by the Earth's surface and escapes back into space

  3. Some radiation is absorbed by the Earth's surface and re-emitted as a different form of radiation

  4. This radiation is absorbed by greenhouse gases to produce temperature increase
• Enhanced greenhouse effect


  Human activity has increased the amount of carbon dioxide and methane in the atmosphere, so more radiation is absorbed and less heat escapes into space, leading to temperature increases
• Global warming is causing the world's climate to change
• Effects of climate change

  • Ice caps melting causing rising sea levels
  • Agricultural problems
  • Extremes of weather (e.g. flooding, hurricanes etc)
  • Loss of habitats for plants and animals