ELSS

• What is a system in the context of ELSS

  Any set of interrelated parts
• importance of water to life on earth

  • water provides a medium that allows organic molecules to mix and form more complex structures.
  • water makes up to 65-95% of all living organisms which is crutial to their growth.
  • water is a resource to economic activity, to generate electricity.
  • water helps to create benign thermal conditions, oceans occupy 71% of the earths surface.
  • plants require water for rigidity and to transport mineral nutrients from the soil.
• What causes overland flow?

  Infiltration excess overland flow and saturated overland flow.
• The input in the water cycle is precipitation
• Processes of the water cycle system

  condensation

  evaporation

  evapotranspiration

  stemflow

  surface run off

  percolation

  infiltration

  ground water flow
• What are the stores of the water cycle system

  cloud

  vegetation

  ice

  snow

  oceans

  rivers

  aquifers

  lakes/reservoirs
• what are the outputs of the water cycle system?

  rivers

  human uses
• How does spatial factors influence the stores and flows of the water cycle?

  At higher latitudes there are more ice stores

  around the equator there are more water stores in vegetation (rainforests)

  0° latitudes there are ice stores on mountains

  more evaporation in summer in the mid-latitudes
• What are temporal factors influencing stores and flows of the global water cycle?

  Day and night (hot and cold) evaporation. Transpiration in the day and none at night globally.

  seasons

  Milankovitch cycles

  Glacial and inter-glacial periods (more water on land vs oceans)
• How is carbon important to life on earth?

  Common chemical element - stored in carbonate rocks such as limestones, sea floor sediments and ocean water etc

  Life is built on carbon - proteins, carbohydrates etc

  Economic resource - fossil fuels , coal oil and gas

  Carbon usage in products such as plastics and paint

  Agricultural crops and forest trees store large amounts of carbon and are used for food, timber, paper and textiles
• How much carbon is stored long term in sedimentary rocks?

  99.9%
• What % of water is stored in oceans ?

  97%
• What are inputs to the water system?

  Water evaporated from oceans, soils, lakes and rivers

  Vapour transpired through the leaves of plants.

  Together these processes are known as evapotranspiration
• Outputs of the water cycle?

  Leaves the atmosphere through precipitation and condensation

  Ice sheets, glaciers and snowfields release water by ablation (melting and sublimation)
• Throughputs of the water cycle

  Run-off

  Infiltration

  Percolation into aquifers
• How many billion tonnes of carbon is stored in sedimentary rocks?

  60,000 - 100,000,000
• How many billion tonnes of carbon is stored in the oceans?

  38,700
• What is flux?

  the rate of energy transfer per unit area