OCR A-Level Geography H481
Coastal Landscapes
Glaciated Landscapes
Dryland Landscapes
Earth’s Life Support Systems
Changing Spaces; Making Places
Trade in the Contemporary World
Global Migration
Human Rights
Power and Borders
Climate Change
Disease Dilemmas
Exploring Oceans
Future of Food
Hazardous Earth
Geographical Skills
Glaciated Landscapes
Glacier mass balance and the equilibrium line
- 3 things to know
- Component 01
Overview
Recall questions on glacier mass balance, accumulation, ablation and sublimation, the accumulation zone and equilibrium line, the seasonal balance of an Alpine glacier, water equivalent and net balance calculations, the accumulation area ratio, and why a snout advances or retreats only after a lag.
What you need to know
Answer each one before you reveal it.
Why is mass balance measured in metres of water equivalent rather than metres of snow?
Explain why there is a lag between a negative mass balance and a visible retreat of the snout.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define glacier mass balance.
Model answer
It is the difference between the mass a glacier gains by accumulation and the mass it loses by ablation over a given period, usually a year.
- 2
What is accumulation?
Model answer
It is all the processes that add mass to a glacier, chiefly snowfall, together with avalanching, wind-blown snow and rain freezing onto the surface.
- 3
What is ablation?
Model answer
It is all the processes that remove mass from a glacier, chiefly melting, together with sublimation, wind erosion of snow and the calving of icebergs.
- 4
Name the process by which ice turns directly into water vapour.
Model answer
Sublimation.
- 5
Where on a glacier is the accumulation zone found?
Model answer
In the upper part of the glacier, above the equilibrium line, where annual gains of snow exceed annual losses.
- 6
What is the equilibrium line on a glacier?
Model answer
It is the line where accumulation exactly equals ablation over a year, separating the accumulation zone above from the ablation zone below.
Other ways to work this
The same content, four other ways.
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