The water cycle

• What is convectional rainfall?


  due to heating by the sun, warm air rises, condenses at higher altitudes and falls as rain
• What is relief rainfall?

  warm air is forced upwards by a barrier such as mountains, causing it to condense at higher altitudes and fall as rain
• What is frontal rainfall?

  warm air rises over cool air when two bodies of air at different temperatures meet, because the warm air is less dense and therefore lighter it condenses at higher altitudes and falls as rain
• What is an example of an input in the water system?

  precipitation
• What is precipitation?

  any water that falls to the surface of the earth from the atmosphere
• What are examples of flows/transfers in the water system?

  • surface runoff
  • channel flow
  • overland flow
  • infiltration
  • percolation
  • throughflow
  • groundwater flow
  • stemflow
• What is surface runoff?

  the movement of water o er the earths surface - divided into channel flow and overland flow
• What is channel flow?

  water flowing in a river channel
• What is overland flow?

  water flowing across the land
• What is infiltration?

  vertical movement of water from the earths surface into the soil
• what is percolation?

  vertical movement through rock underground
• What is throughflow?

  horizontal flow of water through sub surface rock responding to gravity or underground water pressure variations
• What is groundwater flow?

  horizontal flow of water through sub-surface rock responding to gravity or underground water pressure variations
• What is stemflow?

  water that has been intercepted by vegetation may drop down trees or flow down stems and trunks to reach the ground
• What are examples of stores in the water cycle?

  • oceans
  • ice sheets
  • groundwater
• What are examples of outputs in the water cycle?

  • evapotranspiration
  • streamflow
• What is evapotranspiration?

  The process by which water is transferred from the land to the atmosphere through evaporation from the soil and transpiration from plants.
• What is streamflow?

  all water that enters a drainage basin will either leave through the atmosphere or through streams which drain the basin. These may flow as tributaries into other rivers or into lakes and oceans.
• How much water does the hydrosphere contain?

  1.4 sextillion litres
• How much water in the hydrosphere is freshwater?

  less than 3%
• How much of the earths freshwater is frozen in the cryosphere?

  69%
• How much of the earths freshwater is groundwater?

  30%
• How much of the earths freshwater is stored on the earths surface?

  0.3%
• How much of the earths freshwater is stored as water vapour in the atmosphere?

  0.04%
• What type of system is the global hydrological system?

  Closed
• How does the magnitude of the evaporation flow vary by location and season?

  • lots of solar radiation, large supply of water, warm dry air= high
  • vice versa
• What is condensation?

  when water vapour changes state to become a liquid - when air containing water vapour cools to its dew point
• What does the magnitude of the condensation flow depend on?

  amount of water vapour in the atmosphere and the temperature
• How do clouds form?

  warm air cools down, causing water vapour to condense into droplets which gather as clouds
• What causes warm air to cool?

  other air masses, topography, convection
• What cryospheric processes change the amount of water stored as ice?

  accumulation and ablation
• What is a river’s drainage basin?

  the area surrounding the river where the rain falling in the land flows into that river
• What is the boundary of a drainage basin?

  the watershed
• Are drainage basins open or closed systems?

  open
• What is the primary input in a drainage basin?

  Precipitation
• what are the water outputs in a drainage basin?

  runoff, evaporation, transpiration
• How is soil storage a store in a drainage basin?

  water is stored around and between soil particles in the pedosphere
• How is channel storage a store in a drainage basin?

  the volume of water contained within the banks of a river will operate as a water store between its initial input and ultimate input
• How is absorption by vegetation a store in a drainage basin?

  vegetation can withdraw water from the soil, rivers or overland flow via their root systems. The largest proportion of a woodland’s composition is its store of water. This may eventually be returned to the atmosphere by transpiration.
• How is groundwater a store in a drainage basin?

  water is stored within permeable rock underground, entering through gaps between the grains or down joints and cracks in the rock