5.1 global hydrological cycle

• what is the global hydrological cycle

  a closed system containing all of the worlds water, driven by solar energy and gravitational potential energy
• state the two types of energy responsible for the global hydrological cycle

  solar energy (evaporation)

  gravitational potential energy (rivers can flow downhill and precipitation can fall to the ground)
• define closed system

  no inputs or outputs, just contains flows and stores
• what are the stores of the global hydrological cycle

  • ocean
  • groundwater stores
  • surface water stores
  • cryosphere
• define cryosphere

  The frozen layer of the earth
• explain what surface water store is

  includes, rivers, lakes, soil moisture etc
• what are the three freshwater stores

  groundwater

  surface water

  cryoshphere
• explain the composition of the freshwater stores

  groundwater- 30%

  surface water- 1%

  cryoshphere- 69%
• what is the global water budget

  accounts for all the water of the global hydrological cycle
• explain why the earths water budget is problematic

  only 3% of the water is freshwater and only 1% of this is accessible surface water, so water defecits may occur
• what percentage of earths water is accessible

  1%
• what are the two finite water sources

  fossil water and the cryosphere
• example of a meltwater river

  Ganges
• how many glaciers are expected to disappear in the Alps

  3800
• why may the cryosphere not be finite

  if there is another glacial period then more water will freeze
• example of a store with long residency time

  cryosphere- some arctic sea ice has been around for 800,000 years
• why may a short residency time in surface water stores be beneficial

  decreases pollution as polluted water moves through store
• explain the process of the hydrological cycle

  -precipitation hots the ground creating surface run off, but some is intercepted by negation which returns water to local atmosphere via evapotranspiration

  -surface run off travels across many terrains before joining a store

  -some water infiltrates into the ground which joins soil moisture (surface water store) and some percolates through rocks to join groundwater storage

  -groundwater ,over extremely slowly (long residency time) but eventually joins stores

  -water in stores evaporated due to solar energy and rides. It cools and condenses (heavy air travels a long way) and falls as precipitation

  -some water vapour joins crysophere