February 11th lecture

Question 1

What is the Albedo Feedback loop?

Answer 1

• Melting of sea ice leads to….
• Lowered Albedo leads to….
• Increased absorption of sunlight leads to…..

Question 2

How does increasing the salinity of sea water alter the freezing point?

Answer 2

The higher the salinity the lowers the freezing point.

Question 3

What temperature does normal salinity level sea water freeze at?

Answer 3

-1.8C

Question 4

What is Brine rejection?

Answer 4

It is the process of salt being squeezed into the water belowt due to the surface layer of ice being frozen

Question 5

What does brine rejection lead to? ( three main points )

Answer 5

Brine rejection leads to a higher salinity and thus denser water underneath the newly formed ice, leading to this water sinking and mixing with the water masses below.

The increased salinity also leads to the water below the ice having its freezing temperature being lowered

Question 6

What are the seven stages of ice development?

Answer 6

• frazial ice
• grease ice
• pancake ice
• Nilas
• young ice
• first year ice
• Old ice

Question 7

What is Frazial ice?

Answer 7

small spicules and platelets freely suspended in the water coloum

Question 8

What is grease ice?

Answer 8

After the Frazial ice stage when the ice particles have coagulated to form a soupy later on the surface.

Question 9

What are the charicteristics of grease ice?

Answer 9

reflects little light

give the surface a matt appearance

Question 10

How does grease ice behave?

Answer 10

behaves in a
viscous fluid-like manner, and does not form distinct
ice floes

Question 11

What is pancake ice?

Answer 11

Circular peaces of ice from 30cm - 3m in diameter, and up to 10cm in thickness with a raised rim due to collisions with other pancake ice patches

Question 12

How do ice sheet increase in thickness?

Answer 12

Once a sheet of ice has formed, it can increase in thickness

by the freezing of water on its lower surface.

Question 13

How can the water below the ice surface freeze?

Answer 13

When the air above the ice is colder than the water below the
ice, heat is removed by conduction through the ice from the
water to the air above

Question 14

The rate at which heat flows from the water is?

Answer 14

Proportional to the temperature difference between air an water

and is inversely proportional to the thickness of the ice layer and the snow cover on top of the ice.

Question 15

How does young ice form?

Answer 15

• Forms under quiet conditions

Question 16

How thick are dark nilas?

Answer 16

less than 5cm thick

Question 17

How thick are Light nilas?

Answer 17

5-10cm thick

Question 18

How thick is grey ice?

Answer 18

10 - 15cm thick

Question 19

What is finger rafting?

Answer 19

when ice breaks almost like a pumkins smile

Question 20

What is first year ice?

Answer 20

• 30cm thick
• can be up to 2.0m thick or thicker
• Associated with not more than 1 winter’s growth

Question 21

What are gaps between ice floats called ?

Answer 21

fractures or

leads

Question 22

What is multi year ice?

Answer 22

old ice that has survived at least 1 summers melt

Question 23

What happens to the salt conentration in ice as it gets older?

Answer 23

The salt concentration gets smaller

Question 24

As ice gets thicker and less dense what happens to it?

Answer 24

It starts to stand more and more out of the ocean

Question 25

How thick is multi year ice?

Answer 25

6-7+ m thick

Question 26

What is the radar backscatter and microwave emissivity of multi year ice? Why?

Answer 26

Due to its lower
salinity, has higher
radar backscatter and
lower microwave
emissivity

due to this we can see it from satellites easily

Question 27

what does satillite data show about Multi year ice

Answer 27

There is less and less of it every year, and it is thinning

Question 28

What are polynyas?

Answer 28

sections of open water during winter due to a broken ice sheet

Question 29

How do polynyas occur?

Answer 29

A polynya forms when
winds push the ice
away from the coast or
fast ice, resulting in
the recurrent presence
of open water even
during winter.

Question 30

Why are plolynyas importnat?

Answer 30

They allow marine life in the polar region to surface and have have sunlight

Question 31

What is a iceburg

Answer 31

An Iceberg is a massive piece of ice
of greatly varying shape, which has
broken away from a glacier or ice
shelf and which may be afloat or
aground

Question 32

are glaciers fresh or salt water?

Answer 32

Since they come from glacial ice, i.e.

snow, they are fresh

Question 33

How are iceburgs controlled?

Answer 33

by water currents mainly

Question 34

Does wind affect glacier movement?

Answer 34

Winds become more important to icebergs having high sail to draft ratio
or high ratio between the above water to below water portion