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
Firn, glacier ice, valley glaciers and ice sheets
- 3 things to know
- Component 01
Overview
Recall questions on how snow becomes firn and then glacier ice, the densities involved, why glacier ice looks blue, the role of meltwater, and valley glaciers, ice caps, piedmont glaciers and the Antarctic and Greenland ice sheets.
What you need to know
Answer each one before you reveal it.
Outline the stages by which fresh snow becomes glacier ice.
Why does dense glacier ice appear blue?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is firn?
Model answer
Firn is snow that has survived at least one summer melt season and has been compacted into a dense, granular mass.
- 2
Outline the stages by which fresh snow becomes glacier ice.
Model answer
Fresh snow is compressed and its crystals round off, air is squeezed out to leave firn, and continued burial with melting and refreezing turns the firn into dense glacier ice.
- 3
What is the approximate density of freshly fallen snow?
Model answer
About 50 to 100 kg m⁻³.
- 4
State the approximate density of glacier ice.
Model answer
About 900 kg m⁻³.
- 5
At what density is compacted snow regarded as having become glacier ice?
Model answer
At about 830 kg m⁻³, when the air passages between grains seal off into isolated bubbles.
- 6
Why does dense glacier ice appear blue?
Model answer
Bubble-free ice absorbs the longer red wavelengths of light and scatters the shorter blue wavelengths back to the observer.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
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