Earth's life support systems

• How does the earth support life?

  Breathable atmosphere - 21% is oxygen and little carbon which is poisonous (a large amount is in Mars). Our atmosphere is held by gravity.

  Temperature does not fluctuate - all plants receive light for photosynthesis providing us oxygen.

  Axis - Due to the rotation provided we have day and night the gravity of the sun allows us to orbit without it the earth would float away
• Define what is meant by Goldilocks zone.


  The right distance from the sun to allow the presence of water
• How does the earth's temperature not fluctuate?

  Oceans absorb heat and release it back slowly

  Clouds in the atmosphere contain water droplets and ice crystals which reflect 1/5 of solar radiation

  Water vapour maintains the temperature 15 degrees higher than what it would otherwise be.
• What are the 3 main stores in the water cycle?

  Atmosphere

  Oceans

  Land
• How much water does each store, store?


  Oceans - 97%

  Atmosphere - 0.001%

  Land - Other percentage
• Why does the atmosphere have such little water?

  Rate of condensation precipitation exceeds the rate of evaporisation
• What is stores measured in?

  Thousands of cubic kilometers (km^3 x 10^3)
• What are flows measured in?

  Thousands of cubic kilometers per year (km^3 x 10^3 / year)
• Define a flux.


  Measurement of the rate of flow of material between stores. Measured in mass / time
• Define a process.


  The physical mechanism which drives the flux of material between stores
• Define a drainage basin.


  An area of land that is drained by a river and its tributaries
• What system is a drainage basin?


  Open because both mass and energy cross its boundaries
• Describe the role of precipitation in the carbon cycle.

  The atmospheric CO2 dissolves into rainwater to form a weak carbonic acid. Despite being natural CO2 concentrations have increased the acidity of rainfall, which increases the acidity of ocean surface waters and can be harmful to marine life.
• Describe the role of photosynthesis in the carbon cycle.

  Energy from the sun, CO2 and water are used by plants and phytoplankton to make glucose. This glucose is then made to maintain plant growth and release CO2 back via respiration.
• Describe the role of weathering in the carbon cycle.

  The stationary breakdown of rocks on the earth surface by chemical, physical and biological processes. Rainwater then has CO2 and can dissolve limestone and chalk through carbonation.
• Describe the role of carbonation in the carbon cycle.

  Carbonation releases carbon from limestone into water sources and works best beneath a soil cover due to highly acidic rainwater.
• Describe the role of chelation in the carbon cycle.


  Helps rocks breakdown during biological weathering. Rainwater mixed with dead organic matter forms humid acids which attack rock minerals. Important for forest trees to produce leaf litter.