Cold Environments Book 1 Flashcards
What is the difference between total accumulation total ablation for the whole of the glacial year called?
The glacial budget
Describe a polar glacier
The temperature of the ice remains well below freezing so it remains frozen to the bedrock so there is very little ice movement or erosion
How does gravity influence the flow of ice?
The downhill force of the ice encourages it to move. The steeper the gradient the greater the pull of gravity
In the summer what lubricates glaciers in Alpine areas?
Melt water helping them move down Valleys
How does the temperature of ice influence its flow?
If the ice is too cold it will simply freeze to the bedrock like in Greenland and Antarctica in more temperature environments such as Alaska temperatures are higher so there is more melt water
How does the mass of ice influence its flow?
The heavier the ice the more potential energy it has but it must overcome more friction ice masses don’t generally move until the thickness exceeds 60 m the greatest velocity of movement is at the firn line
What is the term for when ice changes directly from a solid to a vapour?
Sublimation
Is the Southern Ocean rich in animal life?
Yes despite being very cold
What do glacial or polar areas tend to be covered by?
Ice sheets and glaciers
What is the dividing line between the zone of accumulation and zone of ablation called?
The firn or equilibrium line
Describe the compressional flow
It occurs below the third line and it is slower and causes ice to bunch up in areas with less steep gradients. Any crevasses created by extension of flow will be closed
Describe basal flow/slippage
The movement of large blocks of ice usually in a series of short jerks. As the glacier moves there is friction, this is overcome by meltwater. The friction and pressure causes melting in the mouth water acts as a lubricant
How cold can winters be in Alpine areas and why?
Temperatures can drop to -10° or less due to high altitude
Where are tundra or periglacial areas found?
Dry high latitude areas such as northern Alaska and Canada, on the edge of polar environments
Why can a glacier be described as a system?
They have input and outputs
Where are the worlds largest glaciers found?
Polar regions
If ablation is greater than accumulation what happens?
Glacial retreat
Are cold environments only land based?
No they also include Maritime environment such as the Arctic and southern oceans
Where are the worlds most actively moving glaciers found?
Alpine areas
How does friction influence the flow of ice?
If the ice moves as one body the friction it exerts on the ground must be overcome
Describe regelation slip
When the glacier meets a small obstacle pressure builds up on the up stream side allowing it to melt and slip over the obstacle on the down glacial side due to a lower pressure the meltwater refreezes
What do Cold environments have a lot of and a little of?
They have a lot of snow and ice and little vegetation, they are sparsely populated
What are the two types of basal flow?
Regelation slip and creep
How does melt water influence ice flow?
It lubricates the ice allowing it to slip down hill
What type of glacier is internal flow the main movement of?
Polar or cold based glaciers
Define a cold environment
They are icy landscapes found at high latitudes (polar) and high altitudes (alpine)
Describe extensional flow
It occurs above the firn line and causes the ice to Exceller rate and become thinner often resulting in crevasses as the ice thins there is less erosion
How does geology influence the flow of ice?
Movement is faster over in impermeable surface as basal meltwater cannot sink into the bedrock
How cold can areas in the Arctic Circle and Antarctic Circle reach?
Temperatures can often drop to -50°C
Describe the winters of Alpine areas
Very cold with heavy snowfall
Describe a temperate glacier
This includes most glaciers outside of Antarctica and northern Greenlund water is present throughout the ice mass and acts as a lubricant, meaning it can move between 20 and 200 m a year. It can erode, transport and deposit material
What is the area near the source of the glacier called?
The zone of accumulation
Describe the ice in the upper and lower layers of a glacier
In the upper layers the ice is more rigid, in the lower layers it can be described as plastic
What is the area near the snout of the glacier called?
The zone of ablation
Describe rotational flow
It occurs between extensional and compressional flow and can be birthplace of a Corrie
What is the PMP at the surface of a glacier?
0° but this drops in the glacier as the ice is under pressure
What are the two types of ice flow?
Compressional and extensional
What does periglacial mean?
“Edge” of glacial
What are the two main outputs of the glacier?
Melting and evaporation
What are the two main components of ice movement?
Internal flow and basal flow
Give examples of polar environments that are land based and marine based
Land based polar environment include Antarctica and Greenland
Sea based polar environment include the Arctic and the Southern Ocean
If accumulation is greater than ablation what process happens?
Glacial advance
What causes glaciers to have a higher erosive power?
Higher inputs relative to outputs
What is a glacial surge?
Where there is huge downhill movement of a glacier, an example would be the variegated glacier in Alaska. Which in the 1980s movie at speeds of up to 65 m a day
Describe creep
This makes the glacier flow more plastically when it meets the larger obstacle it flows around it
Describe the typical budget then an alpine or temperate glacier
It has a positive winter balance and a negative summer balance
What is it called when ice bergs break off the glacier?
Calving
Where are Alpine areas found and what may they contain, give some examples
They are found in high altitude areas and may contain small ice caps, mountain glaciers and tundra environments, examples include the Himalayas and the Alps
Periglacial areas experience permanently frozen ground, what is the technical term for this?
Permafrost
Do polar environments have high levels of precipitation?
No, they are very dry the Antarctic is actually classed as a desert
Where is the fastest movement on a glacier?
In the centre at the top because there is least friction there. On the sides and bass there is more friction meaning there is slower movement
When accumulation and melting are equal what state is the glacier said to be in?
Steady state
What happens in the summer in periglacial areas?
The surface layer thaws enabling hardy plants to grow
Describe the summers in Alpine areas
Relatively warm with temperatures exceeding 20° sometimes
Describe internal flow (internal deformation)
The movement within in glacial ice due to gravity ice crystals orientate themselves in the direction of glacial movement meaning that they can slide past each other. Crevasses develop as the ice moves faster
What is the main input to glaciers and what happens to it over the years?
It is snow, it gradually turns from low-density white ice crystals to high-density clear glacial ice
What is the pressure melting point of ice?
Point at which ice is on the verge of melting
Are periglacial areas permanently covered by ice?
No
In Alpine areas what feed glaciers?
Heavy snowfall
What are the two types of glaciers?
Temperate/warm based or polar/cold based
Name the six factors that influence the flow of ice
- Gravity
- Friction
- The mass of ice
- Meltwater
- Temp of ice
- Geology
