Oceans Chapter 22 - Introduction to Cryosphere and Sea Ice

What are the ways in which pressure ridges are formed?

- From the pressure exerted on the ice by the force if wind or tide. - From thermal expansion

Where is Permafrost located?

Permafrost is located in the Arctic.

How do sheets of ice form?

Sheets of ice form when frail crystals float to the surface, accumulate and bond together. Depending on the climatic conditions sheets may develop from grease and pancake ice.

What is cryosphere?

Cryosphere is a frozen water part of the Earth system.

What is Brine Rejection?

When frazil ice crystals form, salt accumulates into droplets called BRINE, which are typically expelled back into the ocean.

How are Ice sheets formed?

1. Accumulation of snow. 2. Layers on the bottom compress under the pressure of new layers which forms ice.

What are different types of cryospheres?

1. Ice sheets & Ice caps 2. Glaciers 3. Ice shelves 4. Permafrost 5. Icebergs 6. Sea ice

How thick can the multi-year ice get?

6-7+ m thick.

Where do Canadian icebergs come from?

90% of icebergs encountered in Canada are calved from the glaciers of the Greenland.

How do Icebergs form?

Icebergs form when huge chunks of ice calve, break off fro glaciers, ice shelves or glaciers.

How many icebergs get produced?

10,000 - 40,000 are calved annually.

What happens if the ice grows thick enough during the winter?

Accumulated ice will thin during the summer but will not completely melt -> it will remain until the following winter.

Where are ice sheets located?

Antarctica and greenland.

What % of world oceans is covered by sea ice?

Around 15 % of the world oceans is covered by sea ice during a period of the year.

What does Brine Rejection do to the salinity?

Brine Rejection increases the salinity of the near - surface water -> leading to a higher density for the water underneath the newly formed ice. Leading to this water sinking and mixing with the water masses below it.

What are nilas ?

Continuous thin sheets of ice made from grease ice.

Why do polynyas form?

Form from either upwelling warm waters or persistent winds.

How are glaciers formed?

Formed by accumulation of snow that compacts into ice.

How is a cryosphere formed?

Formed due to the accumulation of snow and freezing point .

What are icebergs made of?

Icebergs come from glacial ice, therefore they are considered to be fresh.

What types of ice originate on land?

Icebergs, Glaciers, Ice sheets Ice shelves.

How does oceanic water freeze in calm conditions?

Frazil -> Grease ice -> Nilas

What is pancake ice?

Frazil crystal accumulate accumulate into a slush circular disk called PANCAKE ice.

How does oceanic water freeze in agitated conditions?

Frazil crystal accumulate accumulate into a slush circular disk called pancake ice -> Raised edges or ridges on the perimeter, caused by the pancakes bumping into each other.

What are glaciers?

Glaciers are rivers of ice.

What is grease ice?

Grease ice is is a think and smooth form of ice made from frazil. Grease ice resembles an oily silk.

What is multiyear ice?

Ice sheets which survives multiple summers and is ablate accumulate enough thickness. Once a sheet of ice reaches necessary thickness it can thicken by freezing the water at the lower surface.

What is an ice shelf?

Ice shelfs occur when ice sheets extend one the sea and float on water.

What are icebergs?

Icebergs are massive pieces of ice (larger than 5m) which greatly vary in shape which may be afloat or aground.

What is the function of icebergs?

Icebergs carry nutrients along with freshwater.

Why does the salinity of the sea ice decrease?

It decreases because overtime brine drains out leaving empty air pockets.

What happens when ice is thicker and less dense?

It stands higher out of the ocean.

Why does the brine stay in the liquid state at this stage?

It stays liquid because it would require a lot lower temperature for it to actually freeze. At this stage sea ice has very high salt content.

How are large icebergs controlled?

Large icebergs are controlled mainly by water currents. Winds become more important to icebergs having high sail.

What are some features of the cryosphere?

Leads & Polynyas

What are ice sheets?

Masses of glacial land ice extending more than 50,000 square km

What are ice caps ?

Miniature ice sheets.

Where is multi-year ice more common?

More common in Arctic & rarer n the Atlantic.

What are polynyas like?

More uniform in shape and larger in size. - Usually remain unfrozen for a long period of time.

Where are the most glaciers located?

Most glaciers are located within mountain ranges that show evidence of a much greater extent during the ice ages.

What are leads like?

Narrow, linear

What are frazil crystals?

Needle like crystals. (3 - 4 mm in diameter) Made in oceans.

What happens to leads during the winter?

Open water remains in leads for only a short time before it begins to refreeze.

Where is the cryosphere located?

Poles and places with higher latitudes.

When does rafting occur?

Rafting occurs when two flows are pressed together in such a way that one over-ridges the other in a continuous manner.

What is permafrost?

Region of earth that stays frozen all year.

What is the relationship between age and salinity in regards to ice?

Salinity decreases as ice goes older.

How is sea ice classified?

Sea ice is classified by stages of development that relate to thickens and age.

What is sea ice?

Sea ice is frozen ocean water.

What are the origins of the sea ice?

Sea ice originates in Oceanic water. Sea ice grows during the winter months and melts during the summer months. However some SEA ice remains in the same regions year round.

What happens to some brine droplets?

They become trapped in pockets between the ice crystals.

How long does it take Icebergs from Greenland to Reach Newfoundland?

Takes from 2 - 3 years.

Why do the leads form?

They form because of the motion of the ice.

What happens when temperatures increase in spring and summer?

The first year ice begin to melt. If the FIRST YEAR ICE will not get thick enough during the winter it will completely melt down during the summer.

What happens once sea ice forms into ice sheets?

Those ice sheets continue to grow through the winter.

How does freezing occur in the oceanic waters?

When ocean water freezes small needle like ice crystals called FRAZIL form (3 - 4 mm in diameter)

Do glaciers move?

Yes Glaciers are in continuous slow motion moving downhill with the gravity under its own weight. They periodically retreat or advance depending on the amount of snow accumulation or melting during a season.