Glaciers as natural systems Flashcards
Inputs
Additions to the glacial system, e.g. snowfall, avalanche, debris – main input is snow, over time becomes compacted and turns to high density glacial ice
Outputs
Things that leave the glacial system, e.g. meltwater, evaporation, sublimation, moraine deposition – main output is meltwater from the snout, calving major output where the glacier extends over the sea and large pieces of glacier break off
Energy
A glaciers mass combines with the gravitational force to generate potential energy, as the glacier moves the potential energy is converted to kinetic energy allowing the glacier to carry out processes, e.g. erosion, transportation, deposition – meltwater facilitates the conversion to kinetic energy
Stores/components
Mass that glaciers hold – main stores is snow and ice, often seasonal variations in the magnitude of stores, 3 types of glacial stores: subglacial (underneath the glacier), englacial (within the glacier) and supraglacial (on top of the glacier)
Flows/transfers
Transfer of mass or energy, e.g. internal deformation, basal sliding, meltwater flow – many transfers of energy, more active in warmer season and in alpine glaciers rather than polar glaciers.
Positive feedback
Occurs where the effects of an action are sped up promoting rapid change (melt or grow), heightening the first process, e.g. ice expands over an area causing an inc in albedo, more solar radiation is reflected back into space, less radiation is absorbed by the surface, temperatures dec, promotes further growth of glaciers, e.g. increased greenhouse warming, increased warming of tundra surface, permafrost melts, methane and carbon dioxide released
Negative feedback
Occurs where the regulatory function are performed to est equ again (doesn’t melt or grow), counteracted by oppo process, e.g. Greenland ice sheets start to melt, causes freshwater to enter the North Atlantic, this desalinised water making less dense, may affect North Atlantic drift reducing its effect causing temperatures to drop by 2 degrees C in north-western Europe, the melting of the ice sheet is halted by the drop in temperature, e.g. temperature inc, warm temperatures expose more land that was previously covered, more plants can survive and sequestrate carbon from the air, greenhouse effect lessens, temperatures fall
Dynamic equilibrium
When landforms and processes are in a state of balance: in a glacier, the equ line marks the boundary bet accumulation (inputs) and ablation (outputs) zones, as the balance shifts the equ line will move up or down the glacier making it dynamic equ determined at the end of the ablations session (September)
