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Earth System- 29992 > Cryosphere 1- introduction > Flashcards

Cryosphere 1- introduction Flashcards

1
Q

What are the main general parts of the atmosphere?

A

Snow
Sea ice
Ice shelves
Ice sheets
Glaciers and ice caps
Permafrost continuous
Permafrost discontinuous, isolated

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2
Q

What are the timescales for lifetime/ rate of change in different parts of the cryosphere?

A

Snow - day to month (seasonal)
River and lake ice - seasonal
Glaciers and ice caps- seasonal to century
Frozen ground- daily to millennium
Ice sheet margin- monthly
Ice shelves- yearly
Ice sheet- millennium

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3
Q

What are the 2 present day ice sheets in the cryosphere?

A

Greenland
Antarctic

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4
Q

Where can permafrost be found?

A

Siberia
Northern Russia
Northern north America

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5
Q

What is permafrost?

A

permanently frozen ground at a certain depth

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6
Q

What is the active layer when considering permafrost?

A

the top most layers that will experience seasonal freezing and thawing

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7
Q

What can lead to the changing of lifespan for different parts of the crysosphere?

A

climate forcing - warming, cooling, changing weather patterns

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8
Q

What affects how quickly a reservoir will react with the environment?

A

the size of reservoir

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9
Q

What would happen to sea level if the Greenland ice sheet instantly melted?

A

would rise by around 8m

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10
Q

What would happen to sea level if the Antarctic shelf melted instantly?

A

50 m rise

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11
Q

What is the last largest ice sheet which is no longer present?

A

the Laurentide

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12
Q

Where was the Laurentide ice sheet located?

A

North America extended past New York and Mid-west to Rockies

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13
Q

How has ppm of CO2 changed over time? (numbers)

A

present day - 420
Pre Industrial revolution - 280
Last glacial maximum - 180

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14
Q

How much lower was sea level 22 Ka?

A

180m lower at max ice sheet size
120m average for ice age (last 80 Ka)

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15
Q

Why was sea level lower in the last glacial maximum?

A

the water becomes locked in ice sheets

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16
Q

What happens when a continental ice sheet becomes large enough?

A

pushes to edge of continental land then land dips down leading ice to float on top of the water

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17
Q

What does ice that floats on water form? (when still attached to main ice sheet)

A

Ice shelves

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18
Q

What is ice berg calving?

A

ice berg creation this is when ice breaks off from the edge of the ice shelf

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19
Q

What will the stability of floating ice generally be like?

A

Inherently unstable

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20
Q

What is buttressing with ice shelves?

A

how the ice shelf interacts with the topography beneath it especially high points

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21
Q

What can happen to ice contact with underlying topography is there is any rise in sea level?

A

ice lifted off these points causing fractures and breaks increasing melting risk from both sides ocean below and atmosphere above

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22
Q

Why are strong Katabatic winds present in the Antarctic?

A

due to change in altitude and temperature regional density currents are created

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23
Q

What is the effect of the strong Katabatic winds on the ice shelfs and ice margin environment?

A

push sea ice away from ice shelf
creating an open water area

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24
Q

How do katabatic winds lead to upwelling?

A

winds create current which pushes surface water away by wind meaning deep nutrient rich water rises to take place

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25
Q

What do ice streams do to the energy in ice sheets?

A

focus energy allowing movement of ice in plastic form
Act as river system bringing ice mass to edge

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26
Q

When did the Larsen B ice shelf break up?

A

98-01

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27
Q

What were the stages that lead to the break up of Larsen B?

A

Cracks appeared which filled with meltwater leading to huge calving event (explosion/ shattering of shelf)

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28
Q

What problems arise form large ice shelves like Larsen B breaking up?

A

expose land ice behind making calving and melt more likely which can significantly affect sea level

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29
Q

What are the 2 main types of mountain glacier?

A

Cirque
Valley

29
Q

What is a cirque?

A

circular bowl shape cut into mountain side

30
Q

What is an arete?

A

when two headwalls of cirque erode back to back creating a knife edge ridge

31
Q

What can lead to the formation of a pyramidal peak?

A

3 or more cirques erode back to back creating a steep pointed peak

32
Q

What is the transition of mountain glaciers like?

A

Cirque will flow into a small valley glacier which will in turn flow into the main valley glacier

33
Q

What is an examples of a valley glacier?

A

Franz Josef New Zealand

34
Q

What will valley glaciers do to the surrounding valley?

A

erode and smooth it down creating a U-shaped valley

35
Q

What do U shaped valleys provide a visual reminder of in the UK?

A

Glaciated past of the British isles

36
Q

What is a piedmont glacier?

A

when the valley ends and the glacier flows into an open lowland area it will spread out showing how glaciers can be plastic (weight and heat)

37
Q

What is an example of a piedmont glacier?

A

elephant foot glacier Greenland

38
Q

What is a nunatak?

A

when some of the mountainous topography sticks out the top of the glacier

39
Q

How can you tell nunataks from the surrounding rock?

A

as they lie above the glacial erosivity line they are instead affected by freeze thaw for will be weak/ easier to break with hammer

40
Q

How much of fresh snow is air? (first stage glacial ice formation)

A

90%

41
Q

What will happen to fresh snow with continual compaction?

A

it will transition into firmer more dense layers until glacial ice is formed

42
Q

How much air is in granular ice? (2nd stage of glacial ice formation)

A

50%

43
Q

How much air is in firn? (3rd stage og glacial ice formation)

A

20-30%

44
Q

How much air/ air bubbles are present in glacial ice?

A

20%

45
Q

At what rate does Greenland ice accumulate?

A

50cm yr-1

46
Q

At what rate does Antarctica ice accumulate?

A

5cm yr-1

47
Q

How can seasonal variation be seen in ice cores?

A

will be a darker summer layer and lighter winter layer which form one year

48
Q

What is the important factor that can be measured in ice cores?

A

The gas bubbles they contain can be radiometrically dated to used to analyse past climate composition

49
Q

What is an archive?

A

record of information (not how stored just where)

50
Q

What are ice archives key evidence of the connection between in?

A

the atmosphere

51
Q

What past variables can be found through ice cores?

A

Temp
CO2
Dust

52
Q

How might the Milankovitch cycles link to the saw tooth pattern of past temperature?

A

Cooler interglacial 100 Ka cycle maybe linked to eccentricity
warmer interglacial 40 Ka time scale maybe linked to obliquity
20 Ka peaks in these period procession

53
Q

What was pre-industrial CO2 PPM like?

A

180-280ppm 100ppm range due to sheet shift and sea level change

54
Q

Why is dust concentration typically higher in glacial periods?

A

due to colder air which can hold less moisture/ water vapour- dry atmosphere- dust production

55
Q

What is glacial mass balance?

A

the balance between input and output from a glacier

56
Q

What is the zone of accumulation?

A

area of added mass to a glacier accumulation greater than ablation
Usually lighter due to fresh snow

57
Q

What is the zone of ablation?

A

greater ablation than accumulation
Darker/ dirty due to material present
Where loss of glacial mass occurs

58
Q

How do glaciers move?

A

Combination of 3 factors:
1&2) internal flow in solid ice
3) Sliding along the base

59
Q

What type of glacier is internal flow more common in?

A

cold based glaciers as the ice is stuck to the bedrock

60
Q

What basic physics is internal flow defined by?

A

thickness
density
acceleration
sin/ angle of slope

61
Q

What counteracts internal flow?

A

friction

62
Q

How do warm based glaciers predominantly move?

A

basal slip where water acts as lubrication between rock and ice
(meltwater produced as PMP lowers melt temp slightly)

63
Q

What temp of ice will cold glaciers be made of?

A

only cold ice which is very strong and well below freezing point

64
Q

What will warm glacial ice co-exist with?

A

water at pressure melting point

65
Q

What is pressure melting point?

A

when the melting point is lowered under a column of ice

66
Q

What temp of ice are temperate glaciers made of?

A

only warm ice
apart from top 10-15m in winter

67
Q

What are polythermal glaciers?

A

they have both warm and cold ice

68
Q

What allows water to move around the glacial system?

A

complex plumbing system of supra and sub glacial streams combined with moulins and supraglacial ponds

69
Q

What is the problem with the formation of melt-ponds in the supraglacial environment?

A

Darker low albedo go through 90 to 10% reflected
feeds positive feedback

70
Q

What is the problem with meltwater ponds and moulin production?

A

Meltwater can sink and erode its way through the glacial ice creating a hole/ channel to the sub-glacial environment allowing vast amounts of meltwater to base lifting glacier making movement easier and shifting more mass to ablation zone.

71
Q

How can deforming beds be a way of glacial movement?

A

if sediment under glacier instead of rock they will deform faster so less obstruction to movement

Earth System- 29992 (24 decks)

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