Cold Environments Flashcards
What is albedo?
Where snow and ice reflect most incoming solar radiation, creating a permanent deep freeze
How does frost weathering work?
Water, trapped in confined rock joints or crevasses, expands by 9% of its volume on freezing, which shatters the rocks
What several factors control the effectiveness of freeze-thaw weathering
The number of freeze thaw cycles
The availability of moisture
The density of jointing I’m rocks
What are glaciers?
Are large bodies of ice formed from compressed snow
Why do glaciers move?
They move downslope due to their own weight and gravity
What are the three main types of glaciers?
Ice sheets
Ice fields (ice caps)
Valley glaciers
Why do ice sheets submerge the landscape?
Because they often are 2-3km thick
What is the largest type of glacier?
Ice sheets
What are island peaks surrounded by seas of ice due to being covered by glaciers called?
Nunataks
What are ice fields?
Miniature ice sheets covering areas less than 50000 km
What are valley glaciers?
Giant tongues of ice that flow down from the snow line in mountainous regions
What are small mountain glaciers called?
Cirque glaciers
Where are small mountain glaciers often confined to?
Bowl-shaped depressions at the head of glacial valleys
What are valley glaciers that flow from ice fields called?
Outlet glaciers
What are valley glaciers which leave the mountains and spill into lowland regions before merging called?
Piedmont glaciers
What are the three steps in the forming of glacier ice?
Snow
Firm
Glacier Ice
What is ablation?
Melting and sublimation
What converts snow into firn?
Freeze thaw and the weight of overlying snow
What differs firn from glacier ice?
Firn still has some air left
How long does the formation of glacier ice take?
40-50 years
What controls the long term behaviour of glaciers?
Changes in mass balance or annual budget
What does a positive balance do to a glacier?
Increases total mass of ice, causing glaciers to advance
What does a negative balance do to a glacier
Reduces the ice mass and results in glacier retreat
Where does snow accumulate on a glacier?
The zone of accumulation
Where does snow melt
The zone of ablation
What did research in the Cascade Range in the U.S. Pacific Northwest find?
There were 16 years between 1984 and 2006 when glaciers had a cumulative negative mass balance