chapter 7

Question 1

Sea ice is

Answer 1

partly a meteorological and partly an oceanographic phenomenon

Question 2

There are two kinds of floating ice encountered at sea:

Answer 2

Sea ice – formed from sea water and
• Icebergs –form when chunks of ice break off, from glaciers, ice shelves, or a larger iceberg

Question 3

Sea ice is formed in

Answer 3

all waters of the frigid zone in both hemispheres and in parts of temperate zone in winter, particularly in the Antarctic.

Question 4

Sea ice is formed in all waters of the frigid zone in both hemispheres and in parts of temperate zone in winter, particularly in the Antarctic.
• In springtime it

Answer 4

breaks up and spreads into more temperate waters, notably in the Antarctic and western North Atlantic

Question 5

Icebergs are, in general, form in the …….zone in ………………………….

Answer 5

the frigid zone in the North Atlantic area and in both the frigid and temperate zone in the Antarctic.
• In the Antarctic and western North Atlantic they drift well into the temperate zone during springtime.

Question 6

The physics and development of sea ice are

Answer 6

complicated

Question 7

The freezing point of salt water is

Answer 7

lower than that of fresh water

Question 8

The freezing point of salt water is lower than that of fresh water and is governed by its

Answer 8

salinity

Question 9

the higher the salinity the

Answer 9

lower the freezing point.

Question 10

Thus, in the open ocean, water with a salinity of …………………….. start freezing at about ………..

Answer 10

35 ppt (parts per thousand) starts freezing at about‐2 C

Question 11

Thus, in the open ocean, water with a salinity of 35 ppt (parts per thousand) starts freezing at about‐2 C, while in

Answer 11

the Baltic, where salinity of 5 ppt is common, the water starts to freeze at 0.3C

Question 12

The density of sea water

Answer 12

increases with salinity

Question 13

The density also increases with

Answer 13

cooling until a maximum density forthe existing salinity is reached

Question 14

The higher the salinity the

Answer 14

lower the temperature of maximum density.

Question 15

The maximum density of water occurs at about

Answer 15

4C

Question 16

The maximum density of water occurs at about 4 C. On the other hand, sea water with a salinity of

Answer 16

24.7 per cent

Question 17

The maximum density of water occurs at about 4 C. On the other hand, sea water with a salinity of 24.7 per cent, has its maximum density at its freezing point of about

Answer 17

-1.5 C and with higher salinity the temperature of maximum density decreases further.

Question 18

Formation of Sea Ice

Answer 18

• The cooling of surface water increases its density and it sinks, to be replaced by warmer, less dense water from below.
• The process continues until the whole column of water, from top to bottom, has attained its maximum density and all convectional descent ceases.
• Until this stage is reached, ice cannot form

Question 19

formation of sea ice:

At sea it forms more readily where

Answer 19

the water column is stratified into layers of different density.
• In this situation convectional sinking is confined to the topmost layer.

Question 20

Because, with higher salinity the temperature

Answer 20

of maximum density decreases further

Question 21

Because, with higher salinity the temperature of maximum density decreases further, the formation of sea ice can be

Answer 21

a lengthy process

Question 22

Because, with higher salinity the temperature of maximum density decreases further, the formation of sea ice can be a lengthy process, especially in

Answer 22

deep water with high salinity.

Question 23

In some areas, despite very low temperatures, the winter is

Answer 23

not long enough for the process to be completed and sea ice does not form.

Question 24

Sea ice first forms in ……………………….. where the ……………………………..

Answer 24

shallow water where the delay due to convectional sinking is least

Question 25

The development of sea ice begins with

Answer 25

the formation of needle‐shaped crystals called frazil ice.

Question 26

A) The development of sea ice begins with the formation of needle‐shaped crystals calledfrazil ice. B) The frazil ice crystals then

Answer 26

thicken and congeal to form a greasy of soupy layer on the sea surface known as grease ice.

Question 27

A) The development of sea ice begins with the formation of needle‐shaped crystals calledfrazil ice. B) The frazil ice crystals then thicken and congeal to form a greasy of soupy layer on the sea surface known as grease ice.

Answer 27

In the next stage, shuga ice develops, consisting of spongy lumps a few centimeters across

Question 28

A) The development of sea ice begins with the formation of needle‐shaped crystals calledfrazil ice. B) The frazil ice crystals then thicken and congeal to form a greasy of soupy layer on the sea surface known as grease ice. C)In the next stage, shuga ice develops, consisting of spongy lumps a few centimeters across all the above ice are classified generally as

Answer 28

new ice

Question 29

A) The development of sea ice begins with the formation of needle‐shaped crystals calledfrazil ice. B) The frazil ice crystals then thicken and congeal to form a greasy of soupy layer on the sea surface known as grease ice. C)In the next stage, shuga ice develops, consisting of spongy lumps a few centimeters across D)

Answer 29

This is followed by pancake ice, consisting of flat pieces, roughly circular in shape, often with a rim round the edge due to rubbing against adjacent pieces.

Question 30

A) The development of sea ice begins with the formation of needle‐shaped crystals calledfrazil ice. B) The frazil ice crystals then thicken and congeal to form a greasy of soupy layer on the sea surface known as grease ice. C)In the next stage, shuga ice develops, consisting of spongy lumps a few centimeters across D)This is followed by pancake ice, consisting of flat pieces, roughly circular in shape, often with a rim round the edge due to rubbing against adjacent pieces. the pancakes ..........................

Answer 30

gradually join to form a more or less continuous ice sheet, called young ice, this can also be broken up by wave action.

Question 31

Young ice eventually

Answer 31

thickens and becomes field ice or pack ice

Question 32

Young ice eventually thickens and becomes field ice or pack ice, which is a

Answer 32

generic term for all fully developed sea ice floating on the ocean and not attached to the shore

Question 33

Young ice eventually thickens and becomes field ice or pack ice, which is a generic term for all fully developed sea ice floating on the ocean and not attached to the shore; it

Answer 33

varies in thickness from a few inches to several feet

Question 34

floes

Answer 34

Individual pieces of pack ice more than 20 meters across

Question 35

Individual pieces of pack ice more than 20 meters across are called floes and the pack is termed

Answer 35

‘open’, ‘very open’, ‘close’ or ‘very close’ depending on the distance between the floes.

Question 36

Very close pack leaves

Answer 36

little or no water visible

Question 37

Pack ice originating in

Answer 37

Arctic or Antarctic waters

Question 38

Pack ice originating in Arctic or Antarctic waters may be ..................... thick

Answer 38

several feet

Question 39

Pack ice originating in Arctic or Antarctic waters may be several feet thick and

Answer 39

very uneven due to hummocking (piling up) by the waves

Question 40

Icebergs

Answer 40

pieces of ice that formed on land and float in an ocean or lake.

Question 41

Icebergs are pieces of ice that formed on land and float in an ocean or lake. Icebergs come in

Answer 41

all shapes and sizes.

Question 42

The term “iceberg” refers to

Answer 42

chunks of ice larger than 5 meters (16 feet) across.

Question 43

Smaller icebergs, known as

Answer 43

bergy bits and growlers

Question 44

Smaller icebergs, known asbergy bits and growlers, can be especially dangerous for

Answer 44

ships because they are harder to spot.

Question 45

home to most of the icebergs on Earth

Answer 45

The North Atlantic and the cold waters surrounding Antarctica

Question 46

Icebergs form when

Answer 46

chunks of ice calve, or break off, from glaciers, ice shelves, or a larger iceberg. Icebergs travel with ocean currents, sometimes smashing up against the shore or getting caught in shallow waters.

Question 47

Icebergs can develop into a variety of

Answer 47

shapes as they break apart

Question 48

Icebergs pose a danger to

Answer 48

ships traversing the North Atlantic and the waters around Antarctica.

Question 49

Practical Ice Warnings

Answer 49

Provided the ship is non in a specific cold sea surface current, sea surface temperatures might indicate the vicinity of pack ice.

Question 50

A sea temperature of 1C might warn of

Answer 50

an ice edge within about 150 miles

Question 51

if the sea temperature were -0.5 C the ice edfe could be within

Answer 51

50 miles

Question 52

Warning may be given by

Answer 52

ice blink caused by reflection from the ice giving a glare in the sky near the horizon, mainly white if sky is cloudy, and yellow if sky is mostly blue, it is sometimes visible at night.

Question 53

practical ice warnings In fog

Answer 53

white patches indicate ice at short distance

Question 54

A noticeable reduction of sea and swell can warn

Answer 54

of pack ice to windward

Question 55

Small isolated chunks of floating ice may indicate

Answer 55

field ice nearby.

Question 56

Icing on deck occurs due to

Answer 56

sea spray when cold, wave‐generated spray comes in contact with exposed surfaces and the air temperature is below freezing

Question 57

Ice accretion on deck may also occur due either to

Answer 57

the freezing of liquid rain or drizzle drops which come into contact with the vessel or snowflakes freezing onto the vessel.

Question 58

Icing on deck is a serious hazard for

Answer 58

marine operations in high latitude regions

Question 59

Many ships and lives have been lost when

Answer 59

ships sank, or became disabled, after the accretion of ice on decks and superstructures.

Question 60

Dangers of icing on Deck Large amounts of ice can

Answer 60

raise the center of mass on a ship enough to result in a catastrophic loss of stability.

Question 61

........................................................... an occur as a result of the loss of stability and extra weight from the ice burden.

Answer 61

Capsizing, extreme rolling and/or pitching, and topside flooding

Question 62

Capsizing, extreme rolling and/or pitching, and topside flooding can occur as a result of the loss of stability and extra weight from the ice burden. The problem is particularly dangerous for

Answer 62

smaller ships, such as fishing vessels

Question 63

Capsizing, extreme rolling and/or pitching, and topside flooding can occur as a result of the loss of stability and extra weight from the ice burden. The problem is particularly dangerous for smaller ships, such as fishing vessels, because

Answer 63

they are more likely to be exposed to sea spray and a relatively smaller amount of ice is required for destabilization.