EQ2 questions

Question 1

Explain factors that cause variations in the rate of accumulation (6marks)

Answer 1

1. Rates of accumulation vary with climate.
   -Increases in accumulation are caused by high precipitation and low insulation and strong winds. -These strong winds blow snow into hollows and basins so that snow accumulates. -The highest rates of accumulation are thus at higher altitudes on slopes of poleward aspect. As temps are low this means that sublimation and losses are low and meltwater is likely to refreeze.
2. Positive feedback cycles amplify the initial change and if a glacier has a positive mass balance and the glacier surface increases this will increase the albedo of the ice. This will cause even lower temps and initiating positive feedback cycles will cause the glacier to grow and advance.

Question 2

Explain factors that cause variations in the rate of ablation (6marks)

Answer 2

1. Rates of ablation vary with climate.
   Ablation rates increase when there are low levels of precipitation and higher temps.
   As temps are higher at ablation zones this results in melting close to the snout which means there is more water forming as an output where the ice front extends over the water. For example, ice shelves in Antarctica often break off to form icebergs. Thus process is called carving.
2. Negative feedback cycles act to minimize the effect of inputs in order to re-establish stability and maintain equilibrium. e.g if a glacier in dynamic equilibrium is affected by an increase in snowfall at accumulation zones this may increase ice volume and thus the glacier will advance and cause an increase in ice volume at ablation zones

Question 3

Explain the processes that affect the mass balance of temperate glaciers (6marks)

Answer 3

1. Glacial mass balance is the relationship between accumulation and ablation maintenance of equilibrium. .
   The mass balance of temperate glaciers is a consideration of both inputs into the system and outputs. The mass balance will be positive if the accumulation rates exceed ablation and will be negative if ablation exceeds accumulation.
2. Direct precipitation is the most widespread process of accumulation as precipitation that falls directly onto the glacier surface can over time
   form Neve and then Firn and then glacier ice. As this transformation occurs, loosely consolidated ice crystals with interconnecting air passages transform into larger ice crystals with little or no air passages. Surface melting is the most widespread process of ablation. Surface
   melting occurs when the ice surface already at 0C receives further heat. This heat is derived from exposure to radiation and heat exchange with the air in contact with the ice.

Question 4

Explain the importance of ice temp in understanding the rate of glacial movement (8marks)

Answer 4

-Ice temp is crucial in understanding the rate of glacial movement. There are two types where this can occur in temperate and polar glaciers.
-These glaciers experience movement through internal deformation and basal slip
However, temperate glaciers experience movement through both internal deformation and basal sliding. At temperate glaciers the base of the glacier reaches pmp and so basal sliding and surging can occur.
Regelation creep is a sub-movement of basal slip which is where ice flow becomes faster and reaches an obstacle and increased pressure causes it to slowly move over to obstacle in a plastically deform

Question 5

Explain the importance of ice temp in understanding the rate of glacial movement (8marks) PARA 2

Answer 5

Polar glaciers (cold based) are colder and do not reach pressure melting point at their base. Glacier movement is therefore reliant on internal deformation when individual ice crystals change shape in response to pressure (overlying ice) and position of crystals in relation
to each other. The rate of glacier movement is therefore lower in Polar
(cold based) glaciers.

Question 6

Explain the importance of ice temp in understanding the rate of glacial movement (8marks) Para 3

Answer 6

• Ice temperature is not the only factor affecting the rate of glacier movement. Changes in gradient can be important in understanding
  the rate of glacial movement. This is as a result of compressional and
  extensional flow - where it steepens, the rate of glacier movement
  increases and extensional flow occurs, where gradient reduces, the
  rate of glacier movement falls, and ice catches up with ice in front
  causing compressional flow