Glaciation

Question 1

Define mass balance

Answer 1

Difference between inputs (accumulation) and outputs (ablation)
Determines if a glacier grows or shrinks

Question 2

Define the zone of accumulation

Answer 2

Colder higher altitude areas with a positive mass balance (inputs > outputs) where the glacier advances

Question 3

Define the zone of ablation

Answer 3

Warmer lower altitude areas with a negative mass balance where the glacier retreats

Question 4

How does glacial ice form?

Answer 4

New snowflakes fall and compact pre-existing snow.
In summer meltwater percolates into the firn and refreezes to become dense. (Forms seasonal layers with darker stripes)
Over years this repeats and all air is squeezed out of snow forming glacial ice

Question 5

Changes in mass balance over a year

Answer 5

Late autumn to early spring, glacier has a positive mass balance due to cooler temperatures so the glacier advances.
The most rapid accumulation is in winter.

Late spring and early autumn, glacier has a negative mass balance due to warmer temperatures so the glacier retreats.
The most rapid ablation is in summer.

Question 6

Inputs causing accumulation

Answer 6

Precipitation
De-sublimation
Rock debris
Wind blown snow
Avalanche debris
Solar energy

Question 7

Outputs causing ablation

Answer 7

Meltwater
Sublimation
Calving
Rock debris
Wind blown snow