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glaciated landscapes > Unit 1 Notes > Flashcards

Unit 1 Notes Flashcards

1
Q

Why are glaciers important for people?

A

They provide drinking water, help to irrigate crops, can be used for hydroelectric power. 1/3 of the population rely on them.

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2
Q

What is happening to glaciers around the world?

A

They’re shrinking.

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3
Q

How much have sea levels risen by?

A

2.6cm.

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4
Q

Where are glaciers found?

A

Cold areas, close to the poles, at high altitudes.

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5
Q

What is mass balance?

A

The difference between glacial inputs and outputs.

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6
Q

What happens when inputs are more than outputs?

A

A glacier advances.

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7
Q

What happens when outputs are more than inputs?

A

A glacier will retreat.

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8
Q

What is the zone of accumulation?

A

Higher altitude areas where inputs are more than outputs.

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9
Q

What is the zone of ablation?

A

Lower altitude areas where outputs are more than inputs.

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10
Q

What is the line of equilibrium?

A

Where mass balance is equal.

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11
Q

What happens to zones during summer?

A

Zones shift to higher altitudes, zone of ablation increases, zone of accumulation decreases.

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12
Q

What happens to zones during winter?

A

Both zones shift to lower altitudes. Zone of accumulation increases, zone of ablation decreases.

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13
Q

What are the inputs of a glacier?

A

Things which add to the mass of a glacier.

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14
Q

What are the examples of inputs?

A

Snow, Avalanches, Freezing rain, debris wind, wind-blown snow.

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15
Q

Where are inputs concentrated?

A

Towards the head of a glacier.

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16
Q

What are the outputs of a glacier?

A

Things which are lost, making a glacier smaller.

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17
Q

What are the examples of outputs?

A

Meltwater, sublimation, calving, rock debris.

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18
Q

Where are outputs concentrated?

A

Towards the toe of a glacier.

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19
Q

What happens to pre-existing snow when snow falls?

A

It compacts.

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20
Q

What percentage of glaciers are in negative mass balance?

A

75%.

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21
Q

What effect does negative mass balance have on the world’s systems?

A

Increasing global warming, changes to the earth’s albedo, causes sea levels to rise.

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22
Q

Are we in a glacial or interglacial period now?

A

Interglacial.

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23
Q

What is the mass balance of glaciers during a glacial period?

A

Positive mass balance, meaning they can grow and develop into ice sheets.

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24
Q

What was the last glacial period?

A

The Devensian period.

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25
Q

How far along does the Quaternary period stretch?

A

The last 2.6 million years.

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26
Q

What were the last 5 geological periods?

A

Holocene, Devensian, Ipswichian, Wolstonian, Hoxnian.

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27
Q

When does a glacier have a negative mass balance?

A

Between late spring and early autumn.

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28
Q

Why does a glacier have a negative mass balance at this time?

A

Temperatures at this time of year are at their highest.

29
Q

When does a glacier have a positive mass balance?

A

Between late autumn and early spring.

30
Q

Why does a glacier have positive mass balance at this time?

A

Temperatures at this time of year are at their lowest, reducing rates of ablation.

31
Q

What happens to the snow after a number of years?

A

Successive layers of snow and firn accumulate to a depth of 20 metres, and most of the air is squeezed out.

32
Q

What determines the rate at which this happens?

A

Depends on the mass balance equation.

33
Q

What happens to the density of the snow in summer?

A

It becomes more dense, as meltwater percolates into firn, and refreezes.

34
Q

What is firn separated by?

A

Air passages.

35
Q

What is firn snow?

A

Snow which has compacted after a winter’s freezing, and a summer’s melting.

36
Q

What is the density of snow like?

A

Low.

37
Q

What is the cause of the long term cyclical change?

A

Changes in the earth’s orbit around the sun, leading to variation in the intensity of insolation.

38
Q

What are the three types of Milankovitch cycles?

A

Stretch, Tilt, Wobble.

39
Q

How long do stretches last?

A

100,000 Years.

40
Q

What is the difference in insolation between the closest and farthest point from the sun?

A

23%.

41
Q

What does the axis tilt vary from?

A

22.1-24.5 degrees.

42
Q

What does the timeframe vary from of tilts?

A

40,000 Years.

43
Q

What does it mean if the tilt is greater or less extreme?

A

Greater Tilt - More extreme seasons. Lesser Tilt - Less extreme seasons.

44
Q

How long does one wobble cycle last?

A

25,000 Years.

45
Q

What is the Albedo Effect?

A

Cooling of the earth, through sea ice building up, lighter surfaces being created, meaning albedo increases, and sun’s rays are reflected to the atmosphere.

46
Q

What happens to the albedo when temperature increases?

A

Sea ice melts, darker surfaces are revealed, less of sun’s rays are reflected, temperature increases further.

47
Q

What is the negative feedback loop?

A

The idea that an initial change in the glacial budget can bring around lots of other changes as a result.

48
Q

Why is water in NW Europe warm and salty?

A

Initial warming can lead to cooling through thermohaline current.

49
Q

What is the average winter temperature in England vs. Russia?

A

England - 5 degrees. Russia - -8 degrees.

50
Q

How does the amount of salt in the water affect the density?

A

Salty water is more dense.

51
Q

How does the temperature of the water affect the density?

A

Cold water - More dense - sinks. Warm water - less dense - rises.

52
Q

What happened towards the end of the Devensian period?

A

Temperatures were rising, which eventually led to cooling, as it caused disruption in the ocean current.

53
Q

How long did the younger dryas period last?

A

2000 Years.

54
Q

What happened to temperature and ice accumulation during the younger dryas period?

A

Temperature dropped by 15 degrees, Ice accumulation went from 0.75 metres per year to 0.34 metres per year.

55
Q

What did the changes in insolation mean?

A

Icebergs were released into the North Atlantic ocean, reducing density of the remaining ice sheets, ice started retreating.

56
Q

What factors affect short term climate change?

A

Solar forcing, volcanic eruptions, anthropogenic factors.

57
Q

What is solar forcing?

A

The idea that the amount of energy released by the sun changes and is linked to sun spot activity.

58
Q

What are sun spots?

A

Areas of high solar output which fluctuate on an 11 year cycle.

59
Q

What is an example of low solar output?

A

The maunder minimum. Sea ice expanded, Baltic sea froze over. Most of the rivers in Europe also froze over.

60
Q

How do volcanic eruptions affect climate change?

A

Sulphur dioxide and ash are released into the stratosphere, reflecting incoming solar radiation.

61
Q

What are the examples of volcanic eruptions?

A

Laki in Iceland - 1783 - -3 degrees below average. Fambora - 1815 - 0.7 degrees below average.

62
Q

How do anthropogenic factors affect climate change?

A

Human activity increases the concentration of greenhouse gases, meaning average global temperature has risen by over 1.2 degrees since 1880.

63
Q

Why have Antarctic regions warmed by the most?

A

They have warmed by 4.5 degrees, due to the albedo of these environments changing, causing a negative feedback loop.

64
Q

What are the only two ice sheets left?

A

Greenland and Antarctica.

65
Q

What were ice sheets like during the Devensian maximum?

A

There were 7 ice sheets, and they were bigger.

66
Q

What has happened to sea levels as a result of ice sheets shrinking?

A

Sea levels were 130 metres lower then, than they are now.

67
Q

Why are glaciers found at high latitutdes?

A

Lower temperatures are found here, so the sun’s rays are less focused.

68
Q

Why are glaciers found at high altitudes?

A

As warm air rises, it’s under less pressure, expands, and temperature drops as a result.

glaciated landscapes (13 decks)

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