Cold Environments Flashcards
What are glacial environments?
They’re areas covered by ice sheets and glaciers. Glacial environments are found at high latitudes and high altitudes. E.g. Antarctica, Greenland and Iceland
What are periglacial environments?
They’re places where the temperature is constantly below freezing but isn’t permanently covered by ice. They contain a layer of permafrost. They’re found at high latitudes, high altitudes and in the interior of land masses. E.g. Serbia, Canada, Northern Scandinavia, Northern Alaska
What is permaforst?
A layer of permanently frozen ground on or below the surface.
What are alpine environments?
These are cold areas of land at an altitude above the tree line. The tree line is the limit of the area that tree’s can grow. They’re always found at high altitudes and can contain small ice caps, and glacial & periglacial conditions. E.g. Himalayas, Rocky Mountains, the Andes
What are polar environments?
1) The Arctic polar environment - Arctic circle (66N) It’s cold due to a high latitude. The area changes depending on season as melting occurs in summer and re-freezing occurs in winter.
2) The Antarctic polar env - Antarctic Circle (66S) Cold due to high latitude, altitude and conventionality. It’s a huge landmass which includes glacial environments.
What are the glacial inputs?
- Snow (from precipitation)
- Condensation of water vapour from air
- Sublimation of water vapour from the air directly to ice crystals
- Bits of rock collected when the glacier carves away at the landcape, and rocks that have fallen onto glacier from above
What are the glacial outputs?
- Ice can melt and flow out of glacier
- Surface snow can melt and evaporate
- Ice and snow can sublime to form water vapour
- Snow can be blown away by strong winds
- Blocks of ice can fall into the sea to create icebergs - calving
What are glacial stores?
- Ice
- Meltwater
- Debris
What is accumulation and ablation?
Accumulation is the input of snow and ice in the glacial system.
Ablation is the output of water from a glacier.
What is a glacial budget?
The glacial budget is the balance between accumulation and ablation over a year. It shows whether the volume of water in the glacial system has increased or decreased, and so it determines whether the glacier is retreating or advancing.
What are the accumulation and ablation zones?
The accumulation zone is where inputs exceed outputs. The ablation zone is where outputs exceed inputs.
The place where accumulation and ablation are equal is called the glacier’s equilibrium point.
What happens if there’s more accumulation over a year?
If there’s more accumulation over a year, the glacier has a positive mass balance and it advances.
If there’s less accumulation over a year, the glacier has a negative mass balance and retreats.
How do glaciers form?
In cold temperatures, where snow accumulates over a period of time and compresses to form ice.
Water also melts and refreezes in the air spaces making the ice more dense.
Cool summers help due to low ablation rates.
What are warm-based glaciers?
The base is warmer than the melting point of ice. They have water (meltwater) throughout the glacier as the environmental surroundings are warmer. The meltwater acts as a lubricant making it easier for the glacier to move downhill.
Lots of movement = lots of erosion
What are cold-based glaciers?
The base is cold so there’s very little melting. Ice remains frozen to the bedrock so theres very little movement, so cold-based glaciers don’t cause a lot of erosion.
What is internal deformation?
Is where the ice bends and warps to flow downhill. It’s caused by ice crystals shifting past each other. It’s the main way cold-based glaciers move.
It causes crevasses.
What is basal sliding?
It’s the main way warm-based glaciers move.
The meltwater** underneath the glacier allows the glacier toslide over** the ground.
There’s more melting around bits of rock portruding from the valley floor because there’s more pressure on the ice. This can aid movement.
What is extensional flow?
This is at the head of the glacier where the valley is steep. This means there’s a strong gravitational force pulling the ice downwards. This makes the ice move very quickly and when ice moves quickly, there’s more tension which causes the ice to fracture into thick layers. The layers then slip downwards.
What is compressional flow?
This is lower down the glacier where the ice is moving more slowly due to the valley being less steep. The faster ice from the head of the glacier pushes down on the slower ice and compresses it. The high pressure causes the ice to **fractu**re into layers, and the layers slip forwards.
What is rotational flow?
It’s where the glacier moves in an arc shape when it’s in a hollow.
