2.4

Question 1

accumulation zone

Answer 1

where net gain of ice over course of a year. Here in puts exceed outputs

during winter, higher amounts of snowfall and limited melting result in accumulation exceeding ablation

Question 2

ablation zone

Answer 2

where there is a net loss of ice during a year. Here outputs exceed inputs

Ablation at highest during summer (due to rapid melting of the ice)

Question 3

glacier is growing or shrinking, depends on

Answer 3

the balance between accumulation and ablation. The year-to-year change in this budget is known as the mass balance of the ice. It is calculated by dividing the glacier into two zones:

accumulation zone

ablation zone

Question 4

Glaciers advance and retreat in response to long-term trends in the mass balance:

Answer 4

• If accumulation exceeds ablation (leading to a positive mass balance/positive regime), the glacier’s mass increases and it advances.
• If ablation exceeds accumulation (leading to a negative mass balance/negative regime), the glacier’s mass decreases and it retreats.