Glacial System Flashcards
How does Glacier Ice Form?
From Compacted snow, with also hail and sleet which freeze on top of the glacier.
What is the density of granular snow, and how does it go from that to glacier ice.
0.19, and increasingly compacted to form firn. Further pressure compacts it into glacier ice (0.9). Can take from 100-4000 years.
Explain inputs and outputs of the Glacier System.
Inputs: Energy form the Sun, evaporating water to create air masses, which precipitate onto the glacier. Also rock debris.
Processes: Mass as GPE, which is expended as t flows downslope. Energy expended melts ice, which is dissipated.
Outputs: Heat and Water, and GPE is turned into work.
What is Accumulation
The accumulation of glacial matter, in the form of snowfall, icefall and avalanching.
What is Ablation?
Melting, evaporation, sublimaton, calving.
What is the Glacial Equilibrium Point?
The point at which Acc and Ab are equal.
What is moraine?
Debris suspended in the glacier.
What are the processes in the glacier
Ice movement, erosion, transport and deposition.
What is a positive regime?
The glacier increases in mass when Acc>Ab, usually in winter. This causes the glacier to grow and advance at the snout.
What is a negative regime?
When Ab>Acc, usually in summer, causing the glacier to shrink so the snout retreats.
What % of the world’s glaciers are currently experiencing an increase in their negative regime.
75, caused by a result of short-term climate change, surface temps increase from 0.6 to 2 degrees.
What is a steady-state equilibrium
Changes in Acc and Ab do not vary much from long-term conditions. It adjusts in summer and winter, but the average size stays the same.
What is a metastable equilibrium
Glacier changes from one state to another quickly due to an event causing a change in conditions. An example is when subglacial volcanic activity increases ice melting. When the activity ends there is a new equilibrium, with a reduced glacier.
Dynamic Equilibrium
The state of equilibrium changes over a long timescale. CC, causing increased temps, results in Ab always > Acc. The glacier reduces in mass over time.
What is an example of positive feedback that generates a positive regime
Small increases in snow/ice cover increase surface albedo so more solar energy is reflected back into space. This leads to further cooling, further snowfall, and further ice cover.
