14. The Cryosphere

Question 1

What is the cryosphere?

Answer 1

frozen water part of the earth system

Question 2

Where is the cryosphere?

Answer 2

poles and high altitudes

Question 3

Give up to 7 types of the cryosphere

Answer 3

• ice sheets
• ice caps
• ice shelves
• glaciers
• permafrost
• icebergs
• sea ice

Question 4

permafrost=

Answer 4

ground that stays frozen year-round

Question 5

ice sheet=

Answer 5

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

Question 6

how do ice sheets form?

Answer 6

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

Question 7

Where are ice sheets found?

Answer 7

antarctica and greenland

Question 8

___ ____ are miniature ice sheets

Answer 8

ice caps

Question 9

glaciers=

Answer 9

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

Question 10

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

Answer 10

true

Question 11

what are glaciers nicknamed?

Answer 11

rivers of ice

Question 12

ice shelf=

Answer 12

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

Question 13

iceberg=

Answer 13

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

Question 14

How do icebergs form?

Answer 14

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

Question 15

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

Answer 15

western greenland

Question 16

Icebergs are important for transporting ______ and _______

Answer 16

freshwater and nutrients

Question 17

Transport of large icebergs is controlled mainly by what?

Answer 17

water currents

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

Question 18

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

Answer 18

2-3 years avg

Question 19

sea ice=

Answer 19

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

Question 20

For typical ocean salinity, seawater freezes at __C

Answer 20

-1.8C

Question 21

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

Answer 21

15

Question 22

grease ice=

Answer 22

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

Question 23

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

Answer 23

nilas

Question 24

During agitated conditions, what do frazil crystals form?

Answer 24

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

Question 25

Explain the pathway of sea ice formation if conditions are rough

Answer 25

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

Question 26

explain the process of sea ice formation is conditions are calm

Answer 26

calm ocean= congelation growth frazil ice --> nilas --> rafting --> congelation ice --> sheet ice (smooth bottomed)

Question 27

brine rejection=

Answer 27

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

Question 28

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

Answer 28

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

Question 29

Does brine typically remain in a liquid or solid state?

Answer 29

liquid - much colder temps required to freeze brine

Question 30

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)

Answer 30

air decreases

Question 31

First year ice=

Answer 31

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

Question 32

Multi year ice=

Answer 32

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

Question 33

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

Answer 33

0.3-2m relatively level topography low freeboard higher salt content

Question 34

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

Answer 34

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

Question 35

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

Answer 35

freeze the water on its lower surface

Question 36

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

Answer 36

older ice gets= less salt concentration in it stands higher out in the ocean b/c it's less dense= higher freeboard

Question 37

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

Answer 37

false most common in the arctic, rarer in antarctic

Question 38

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

Answer 38

1 grow: from bottom melt: - top - bottom - internal - lateral

Question 39

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

Answer 39

new 10cm

Question 40

Nilas is classified as "___ ice" and is __-__cm thick

Answer 40

young 10-30

Question 41

How thick is 1st year ice? Multiyear ice?

Answer 41

30cm-2m multi= 2+m

Question 42

T/F Sea ice is typically a continuous, uniformly smooth sheet of ice

Answer 42

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

Question 43

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

Answer 43

- from the pressure exerted on the ice by the force of wind/ tide - from thermal expansion

Question 44

When does rafting occur?

Answer 44

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

Question 45

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

Answer 45

leads and polynyas

Question 46

Give some differences between leads and polynyas

Answer 46

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

Question 47

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

Answer 47

coastal= latent open ocean= sensible

Question 48

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

Answer 48

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

Question 49

How is a coastal polynya formed?

Answer 49

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

Question 50

How is an open ocean polynya formed?

Answer 50

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