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EAS 212: The Oceans > 14. The Cryosphere > Flashcards

14. The Cryosphere Flashcards

1
Q

What is the cryosphere?

A

frozen water part of the earth system

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2
Q

Where is the cryosphere?

A

poles and high altitudes

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3
Q

Give up to 7 types of the cryosphere

A
  • ice sheets
  • ice caps
  • ice shelves
  • glaciers
  • permafrost
  • icebergs
  • sea ice
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4
Q

permafrost=

A

ground that stays frozen year-round

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5
Q

ice sheet=

A

mass of glacial land ice extending more than 50,000km^2

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6
Q

how do ice sheets form?

A

formed by accumulation of snow; layers on the bottom get compacted by weight of new layers, forming ice

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7
Q

Where are ice sheets found?

A

antarctica and greenland

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8
Q

___ ____ are miniature ice sheets

A

ice caps

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9
Q

glaciers=

A

a mass of ice in constant slow motion, flowing downhill under their own weight

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10
Q

T/F
like ice sheets, glaciers are also formed by accumulation of snow that compacts into ice

A

true

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11
Q

what are glaciers nicknamed?

A

rivers of ice

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12
Q

ice shelf=

A

when ice sheets extend over the sea and float on the water

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13
Q

iceberg=

A

massive piece of ice (larger than 5m) greatly varying shape, which may be found floating in the ocean or aground

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14
Q

How do icebergs form?

A

when chunks of ice calve, or break off from glaciers, ice shelves, or a larger iceberg

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15
Q

Most icebergs encountered in Canadian waters are calved from the glaciers of:

A

western greenland

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16
Q

Icebergs are important for transporting ______ and _______

A

freshwater and nutrients

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17
Q

Transport of large icebergs is controlled mainly by what?

A

water currents

winds become more important to icebergs having high sail (lots of it is out of the water)

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18
Q

How long does it take for an iceberg to float from the west coast of greenland to the grand banks of newfoundland?

A

2-3 years avg

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19
Q

sea ice=

A

ice that forms, grows, and melts in the ocean
- no origination on land

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20
Q

For typical ocean salinity, seawater freezes at __C

A

-1.8C

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21
Q

__% of the world’s oceans are covered by sea ice during part of the year

A

15

22
Q

grease ice=

A

a smooth, thin form of ice formed by frazil crystals
- this forms during calm conditions

23
Q

grease ice develops into a continuous, thin sheet of ice called

A

nilas

24
Q

During agitated conditions, what do frazil crystals form?

A

pancake ice
= frazil crystals accumulate into slushy circular disks
- raised edges or ridges on the perimeter, caused by the pancakes bumping into each other

25
Q

Explain the pathway of sea ice formation if conditions are rough

A

rough ocean= pancake cycle

frazil ice –> pancake ice –> rafting or ridging –> cementing and consolidation –> sheet ice (rough-bottomed)

26
Q

explain the process of sea ice formation is conditions are calm

A

calm ocean= congelation growth

frazil ice –> nilas –> rafting –> congelation ice –> sheet ice (smooth bottomed)

27
Q

brine rejection=

A

when frazil ice crystals form, salt accumulates into droplets called brine, which are typically expelled back into the ocean

28
Q

What implication does brine rejection have for salinities at different water depths?

A

increases salinity of near-sfc water
–> water underneath the newly formed ice has higher density, so sinks and mixes with water masses below

29
Q

Does brine typically remain in a liquid or solid state?

A

liquid

  • much colder temps required to freeze brine
30
Q

In freshly formed sea ice, there is some liquid brine content. Over time, this drains out, leaving __ pockets and the salinity of the sea ice __(inc/dec)

A

air
decreases

31
Q

First year ice=

A

When temp increases in spring and summer, the sea ice begins to melt. If the ice doesn’t grow thick enough during the winter, it’ll completely melt during the summer = 1st yr ice

32
Q

Multi year ice=

A

if the ice grows thick enough during the winter, it thins during the summer but doesn’t completely melt
- It’ll remain until the following winter, when it’ll grow and thicken again = multiyear ice

33
Q

First year ice is usually __-__m thick. Explain its topography, freeboard (portion about water level) and salt content

A

0.3-2m

relatively level topography
low freeboard
higher salt content

34
Q

Multiyear ice is usually __-__m thick (up to __m). Explain its topography, freeboard (portion about water level) and salt content

A

2-4m up to 7m
more variable topography
high freeboard
lower salt content

35
Q

Once a sheet of ice has formed, how can it increase its thickness?

A

freeze the water on its lower surface

36
Q

How does salinity change as ice gets older? How does this change freeboard?

A

older ice gets= less salt concentration in it

stands higher out in the ocean b/c it’s less dense= higher freeboard

37
Q

T/F

Ice with very high freeboard is more common in the Antarctic than the Arctic

A

false
most common in the arctic, rarer in antarctic

38
Q

Sea ice has 1 way to grow and 4 ways to melt. List them

A

1 grow: from bottom

melt:
- top
- bottom
- internal
- lateral

39
Q

Pancake ice and grease ice are classified as “___ ice” and are less than __cm thick

A

new
10cm

40
Q

Nilas is classified as “___ ice” and is __-__cm thick

A

young
10-30

41
Q

How thick is 1st year ice? Multiyear ice?

A

30cm-2m

multi= 2+m

42
Q

T/F

Sea ice is typically a continuous, uniformly smooth sheet of ice

A

FALSE
it’s a very complex surface that can vary dramatically across even short distances

43
Q

Pressure ridges in sea ice can be formed in 2 ways:

A
  • from the pressure exerted on the ice by the force of wind/ tide
  • from thermal expansion
44
Q

When does rafting occur?

A

when 2 floes are pressed together in such a way that one over-ridges the other in a continuous manner

45
Q

_____ and _____ are regions of open water within an expanse of sea ice

A

leads and polynyas

46
Q

Give some differences between leads and polynyas

A

Leads=
- narrow, linear areas of open water
- form because of the motion of the ice
- during winter, open water remains in leads for only a short time, then refreezes

Polynyas=
- more uniform in shape and larger in size
- form from either upwelling warm water or persistent winds
- usually remain unfrozen for long periods of time

47
Q

What kind of heat would likely be lost from a coastal polynya? What about an open ocean polynya?

A

coastal= latent
open ocean= sensible

48
Q

Why is there a positive feedback loop between climate warming and sea ice loss?

A

The albedo effect

temp rises= sea ice loss= sfc albedo decreases= ocean absorbs more heat= temp rises

49
Q

How is a coastal polynya formed?

A

winds from the shore push newly formed ice away from the coast= open water along the coast.
Brine formation under the newly formed ice results in cold, dense water under the coastal polynya

50
Q

How is an open ocean polynya formed?

A

Upwelling of warmer water.
- colder, dense water sinks
- sensible heat lost through open water

51
Q
A

EAS 212: The Oceans (14 decks)

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