glacial system, budget and net balance

  • Created by: Ali Bland
  • Created on: 16-03-15 19:43
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  • Glacial System
    • The main input is snow
    • The main outputs include ice and meltwater
    • Over many years of snow being compacted, it gradually turns from ice crystals to a clear glacial ice
    • The weigt of the compacted ice combines with gravity to make the glacier move slowly downhill
      • As it does that, it transports sediments and erodes the valley
  • The glacial budget
    • The boundary where gains & losses are balanced is called the equilibrium line
      • Variations in the glacial budget may result in this moving either up or down the glacier, causing the snout to advance or retreat
    • The glacial budget varies during the course of a year
    • The two zones
      • Ablation zone
        • Where there is a loss of ice during a year
          • Here the losses (melting, evaporation) out do the gains
      • Accumulation zone
        • Snow accumulates and forms ice
          • Here the inputs (snow & avalanches) out do the outputs
    • In summer ablation will be its higher, because a rapid melting of the ice
    • In winter, accumulation being greater than ablation
      • In summer ablation will be its higher, because a rapid melting of the ice
  • Net balance
    • This is the difference between the total accumulation and the total ablation during 1 year
    • In termperate glaciers, there is a negative balance in summer when ablation exceeds accumulation,and the reverse in winter
    • If the summer and winter budgets are equal, the glacier appears to be stationary
    • If supply begins to exceed the losses, the snout moves down the valley


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