When the surface of the sea cools to the freezing point temperature in the upper layer of water (several centimeters thick), a large number of disks or plates of pure ice, called sludge, appear. . The thickness of these ice floes is very small, the average size is about 2.5 cm * 0.5 mm, and the shape can be extremely varied - from squares (or almost squares) to hexagonal formations. The optical axis of such a plate is always perpendicular to the plane of its surface. These elemental ice crystals float on the surface of the water, forming the so-called ice grease, which gives the surface of the sea a somewhat oily appearance. In calm water, the plates float in a horizontal position and their from- axes are directed vertically. Wind and waves cause the plates to collide, turn over and take different positions as a result; gradually freezing, they form a permanent ice cover, in which individual crystals are randomly oriented. In the first stage of formation, young ice is surprisingly flexible; under the action of waves coming from the open sea or caused by a moving ship, it bends without breaking, and the amplitude of the oscillations of the ice surface can reach several centimeters.

In the future, if the temperature does not rise, individual plates play the role of embryonic crystals. The mechanism of this process is still not fully understood. As can be seen from fig. 4, ice consists of separate crystals, each of which has purely individual properties, for example, the degree of transmission of polarized light (the same for the entire given crystal, "but different from the others). In some cases, the structural unit of ice is called a grain rather than a single crystal, since it is clear that it has a complex substructure and consists of many parallel plates. The relationship of this substructure to the primary sludge mentioned above is quite obvious. There is no doubt that some of the grain is formed from freezing plates of sludge, which are then stored as separate layers of the crystal. However, some other process also seems to exist, since in some cases the crystals begin to grow on the lower surface of a sufficiently thick ice sheet, and they also have a lamellar structure. Whatever the mechanism for the formation of crystals, all of them - both in sea ice and in freshwater - consist of a large number of plates that are exactly parallel to each other. The optical axis of the crystal is perpendicular to these plates.

Interesting results are obtained by studying the distribution of crystals according to the orientation of their optical axes depending on the depth of their occurrence in the ice mass. Orientation can be characterized by two angles - polar, which is the angle between c-axis both vertical and azimuthal, i.e. an angle measured from some arbitrary direction, such as a north-south line. The values ​​of azimuthal angles usually do not obey any law; rare exceptions to this rule can be caused by unusual tidal events. Polar angles show a certain pattern. As mentioned above, the orientation of crystals near the ice surface is quite variable, since it depends on the effect of the wind during ice formation. But as we go deeper into the ice mass, the polar angles increase, and at a depth of about 20 cm the optical axes of almost all crystals are oriented horizontally. A laboratory study of the freezing of distilled water (Peray and Pounder, 1958), provided that it was cooled from only one direction, and the water was in a calm state, gave the results shown in Table. Horizontal sections were taken from the ice surface and from depths 5 and 13 cm. Each section was examined on a universal polariscope. In this case, the ratio of areas (in percent) occupied by crystals with the same - within 10-degree intervals - orientation of the optical axes was determined.

Orientation of crystals in the ice sheet (Pounder, 1967)

A similar situation is observed in natural sea ice that has reached a certain “age”. Exceptions occur in cases where, during the growth of the ice cover, movements occur that cause compression and fracture of the ice. Thus, the main mass of sea ice that has existed for a year or more consists of crystals whose optical axes are directed horizontally and randomly oriented in azimuth. The length (vertical height) of such crystals reaches 1 m and more, with a diameter of 1 to 5 cm. The reasons for the predominance of crystals with horizontal optical axes in ice help to understand Fig. 4. Since the ice crystal has one main axis of symmetry, it can grow predominantly in two directions. Ice molecules are attached to the crystal lattice either in planes (of the crystal) perpendicular to c-axis and called basal planes , or in the direction of the c-axis, which in turn leads to an increase in the area of ​​the basal planes. Based on the laws of thermodynamics, one can conclude that the first type of crystal growth should be more intense than the second, which is confirmed by experiments.

Rice. five The predominance of the growth of crystals with inclined optical axes, causing the gradual disappearance of the crystal from the vertical from- axis. (Pounder, 1967)

Ice interface -water

Studying the undersurface of growing sea ice helps to understand how water freezes. Lower 1-2 cm ice strata consist of plates of pure (fresh) ice with layers of brine between them. The plates that make up part of a single crystal are parallel to each other and are usually arranged vertically. This is the so-called skeletal (or frame) layer. The mechanical strength of this layer is usually extremely low. With further freezing, the plates thicken somewhat, ice bridges appear between them, and solid ice gradually forms, in which the brine is contained in the form of drops or cells between the plates. A decrease in ice temperature leads to a decrease in the size of the cells filled with brine, which take the form of long vertical cylinders of almost microscopic dimensions in cross section. Such cells can be found in Fig. 4 as rows of black dots along the lines between the plates. A certain number of brine cells are also present at the boundaries between crystals, but the bulk of the brine is contained within individual grains. On fig. 5 shows the results of a statistical study of the thickness of the plates in a sample of annual sea ice. It can be seen that the plates have a uniform thickness, on average within 0.5-0.6 mm. The diameter of nests containing brine is usually about 0.05 mm.

Rice. 6

Sufficient data on the length of such nests is still not available; we only know that it fluctuates over a much wider range than the diameter. Tentatively, we can assume that the length of the nests is about 3 cm.

Thus, we see that in most cases sea ice consists of macroscopic crystals with a complex internal structure - it contains plates of pure ice and a large number of cells containing brine. In addition, ice usually contains many small spherical air bubbles formed from air dissolved in water released during the freezing process. The part of the sea ice volume occupied by liquid - brine, is an extremely important parameter called the brine content. v (Fig. 6). It can be calculated by knowing the salinity, temperature and density of the sea ice. Based on the knowledge of the phase relationships of salt solutions contained in sea water at low temperatures, (Assur, 1958) calculated v for those values ​​of salinity and ice temperature that are found on the globe. Assur's results do not take into account the presence of air bubbles in the ice, but the influence of the latter on the value of v can be determined experimentally by comparing the density of a sea ice sample with the density of freshwater ice at the same temperature. (Pounder, 1967)

Rice. 7 Brine Migration in the Direction of a Temperature Gradient (Pounder, 1967)

3.2. SEA ICE

All our seas, with rare exceptions, are covered with ice of various thicknesses in winter. In this regard, in one part of the sea, navigation in the cold half of the year is difficult, in the other it stops and can only be carried out with the help of icebreakers. Thus, the freezing of the seas disrupts the normal operation of the fleet and ports. Therefore, for a more qualified operation of the fleet, ports and offshore structures, certain knowledge of the physical properties of sea ice is necessary.

Sea water, unlike fresh water, does not have a specific freezing point. The temperature at which ice crystals (ice needles) begin to form depends on the salinity of the sea water S. It has been experimentally established that the freezing point of sea water can be determined (calculated) by the formula: t 3 \u003d -0.0545S. At a salinity of 24.7%, the freezing point is equal to the temperature of the highest density of sea water (-1.33°C). This circumstance (property of sea water) made it possible to divide sea water into two groups according to the degree of salinity. Water with a salinity of less than 24.7% is called brackish and, when cooled, first reaches the temperature of the highest density, and then freezes, i.e. behaves like fresh water, in which the temperature of the highest density is 4 ° C. Water with a salinity of more than 24.7 ° / 00 is called sea water.

The temperature at the highest density is below the freezing point. This leads to the occurrence of convective mixing, which delays the freezing of sea water. Freezing also slows down due to the salinization of the surface layer of water, which is observed when ice appears, since when water freezes, only part of the salts dissolved in it remains in the ice, while a significant part of them remains in the water, increasing its salinity, and therefore, and the density of the surface layer of water, thereby lowering the freezing point. On average, the salinity of sea ice is four times less than the salinity of water.

How does ice form in sea water with a salinity of 35°/00 and a freezing point of -1.91°C? After the surface layer of water has cooled to the temperature indicated above, its density will increase and the water will sink down, while warmer water from the underlying layer will rise up. Mixing will continue until the temperature of the entire mass of water in the upper active layer drops to -1.91 ° ​​C. Then, after some supercooling of the water below freezing, ice crystals (ice needles) begin to appear on the surface.

Ice needles form not only on the sea surface, but throughout the entire thickness of the mixed layer. Gradually, the ice needles freeze, forming ice spots on the surface of the sea, resembling frozen ice in appearance. Salo. In color, it is not much different from water.

When snow falls on the sea surface, the process of ice formation accelerates, since the surface layer is desalinated and cooled, in addition, ready-made crystallization nuclei (snowflakes) are introduced into the water. If the water temperature is below 0 ° C, then the snow does not melt, but forms a viscous mushy mass called snowy. Lard and snowballs, under the influence of wind and waves, break into pieces of white color, called sludge. With further compaction and freezing of the initial types of ice (ice needles, lard, sludge, slush), a thin, elastic ice crust is formed on the sea surface, which easily bends on a wave and, when compressed, forms jagged layers, called nilas. Nilas has a matte surface and a thickness of up to 10 cm, divided into dark (up to 5 cm) and light (5-10 cm) nilas.

If the surface layer of the sea is heavily desalinated, then with further cooling of the water and a calm state of the sea as a result of direct freezing or from ice fat, the surface of the sea is covered with a thin shiny crust, called bottle. The bottle is transparent, like glass, breaks easily in wind or waves, its thickness is up to 5 cm.

On a light wave from ice fat, sludge or snow, as well as as a result of breaking a bottle and nilas with a large swell, a so-called pancake ice. It has a predominantly round shape from 30 cm to 3 m in diameter and up to approximately 10 cm thick, with raised edges due to the impact of ice floes one against the other.

In most cases, ice formation begins near the coast with the appearance of shores (their width is 100-200 m from the coast), which, gradually spreading into the sea, turn into fast ice. Fast ice and fast ice refer to immovable ice, i.e. to ice that forms and remains immobile along the coast, where it is attached to the coast, ice wall, to the ice barrier.

The upper surface of young ice is in most cases smooth or slightly wavy, while the lower surface, on the contrary, is very uneven and in some cases (in the absence of currents) looks like a brush of ice crystals. During winter, the thickness of young ice gradually increases, its surface is covered with snow, and the color changes from gray to white due to the brine draining from it. Young ice 10-15 cm thick is called gray, and a thickness of 15-30 cm - gray white. With a further increase in the thickness of the ice, the ice acquires a white color. Sea ice that has lasted one winter and has a thickness of 30 cm to 2 m is commonly referred to as white first year ice, which is subdivided into thin(thickness from 30 to 70 cm), middle(from 70 to 120 cm) and fat(more than 120 cm).

In areas of the World Ocean, where the ice does not have time to melt during the summer and from the beginning of the next winter begins to grow again and by the end of the second winter its thickness increases and is already more than 2 m, is called two years of ice. Ice that has existed for more than two years called perennial, its thickness is more than 3 m. It has a greenish-blue color, and with a large admixture of snow and air bubbles, it has a whitish color, glassy appearance. With time, freshened and compacted by compression, multi-year ice acquires a blue color. According to their mobility, sea ice is divided into fixed ice (fast ice) and drifting ice.

Drifting ice in shape (size) is divided into pancake ice, ice fields, small broken ice(piece of sea ice less than 20 m across), grated ice(broken ice less than 2 m across), nesyak(a large hummock or a group of hummocks frozen together, up to 5 m above sea level), frosty(pieces of ice frozen into the ice field), ice porridge(accumulation of drifting ice, consisting of fragments of other forms of ice no more than 2 m in diameter). In turn, ice fields, depending on the horizontal dimensions, are divided into:

Giant ice fields, over 10 km across;

Extensive ice fields, 2 to 10 km across;

Large ice fields, 500 to 2000 m across;

Fragments of ice fields, from 100 to 500 m in diameter;

Coarsely broken ice, from 20 to 100 m in diameter.

A very important characteristic for navigation is the concentration of drifting ice. Concentration is understood as the ratio of the area of ​​the sea surface actually covered with ice to the total area of ​​the sea surface on which drifting ice is located, expressed in tenths.

In the USSR, a 10-point ice concentration scale has been adopted (1 point corresponds to 10% of the area covered with ice), in some foreign countries (Canada, USA) - 8 points.

In terms of concentration, drifting ice is characterized as follows:

1. Compressed drifting ice. Drift ice that has a concentration of 10/10 (8/8) and no water is visible.

2. Frozen solid ice. Drift ice at 10/10 (8/8) cohesion and ice floes frozen together.

3. Very cohesive ice. Drift ice with a concentration greater than 9/10 but less than 10/10 (7/8 to 8/8).

4. Closed ice. Drift ice with a concentration of 7/10 to 8/10 (6/8 to 7/8), consisting of ice floes, most of which are in contact with each other.

5. Sparse ice. Drift ice with a concentration of 4/10 to 6/10 (3/8 to 6/8), with a large number of breaks, the ice floes usually do not touch each other.

6. Rare ice. Drift ice in which the concentration is 1/10 to 3/10 (1/8 to 3/8) and an expanse of clear water dominates the ice.

7. Separate ice floes. A large area of ​​water containing sea ice with a concentration of less than 1/10 (1/8). In the absence of ice, this area should be called pure water.

Drifting ice under the influence of wind and currents are in constant motion. Any change in the wind over an area covered with drifting ice causes changes in the distribution of ice: the greater, the stronger and longer the action of the wind.

Long-term observations of the wind drift of packed ice have shown that the ice drift is directly dependent on the wind that caused it, namely: the direction of the ice drift deviates from the wind direction by approximately 30 ° to the right in the northern hemisphere, and to the left in the southern hemisphere, the drift speed is related with a wind speed wind coefficient of approximately 0.02 (r = 0.02).

In table. Figure 5 shows the calculated values ​​of the ice drift velocity depending on the wind speed.

Table 5

The drift of individual ice floes (small icebergs, their fragments and small ice fields) differs from the drift of solid ice. Its speed is greater, since the wind coefficient increases from 0.03 to 0.10.

The speed of movement of icebergs (in the North Atlantic) with fresh winds ranges from 0.1 to 0.7 knots. As for the angle of deviation of their movement from the direction of the wind, it is 30-40 °.

The practice of ice navigation has shown that independent navigation of an ordinary sea vessel is possible with a drifting ice concentration of 5-6 points. For large-tonnage ships with a weak hull and for old ships, the cohesion limit is 5 points, for medium-tonnage ships that are in good condition - 6 points. For ice-class vessels this limit can be increased up to 7 points, and for icebreaking transport vessels - up to 8-9 points. The indicated limits of drifting ice passability are derived from practice for medium-heavy ice. When sailing in heavy multi-year ice, these limits should be reduced by 1-2 points. With good visibility, navigation in ice concentrations up to 3 points is possible for ships of any class.

If it is necessary to navigate through an area of ​​the sea covered with drifting ice, it must be borne in mind that it is easier and safer to enter the ice edge against the wind. Entering the ice with a tail or side wind is dangerous, as conditions are created for the pile on the ice, which can lead to damage to the side of the vessel or its bilge part.

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Sea ice is classified:

by origin,

in shapes and sizes,

according to the state of the ice surface (smooth, hummocky),

by age (stages of development and destruction),

on a navigational basis (ice passability by vessels),

on a dynamic basis (fixed and floating ice).

Origin ice is divided into sea, river and glacier.

Marine ice is formed from sea water, has a greenish or whitish (in the presence of air bubbles or snow) hue.

freshwater ice is carried out in spring and summer from rivers, has a grayish or brownish tint due to inclusions of suspensions.

Glacier ice (of continental origin) is formed as a result of the breaking off of glaciers descending into the sea - icebergs, drifting ice islands.

In appearance and form ice is divided into:

ice needles formed on the surface or in the water column,

ice fat- an accumulation of frozen ice needles in the form of spots or a thin layer of a grayish lead color,

snowstorm- a viscous mushy mass formed during heavy snowfall on chilled water,

sludge– accumulation of lumps of ice, snow and bottom ice,

nilas– thin elastic ice crust up to 10 cm thick,

bottle- thin transparent ice up to 5 cm thick, formed in a calm sea from ice crystals or fat,

pancake ice- ice, usually round in shape with a diameter of 30 cm to 3 m and a thickness of up to 10 cm.

By age ice happens:

young ice 15-30 cm thick, has a gray or gray-white hue,

annual ice - ice that has existed for no more than one winter, with a thickness of 30 cm to 2 m.

biennial- ice that reached a thickness of more than 2 m by the end of the second winter,

perennial pack ice - ice that has existed for more than 2 years, more than 3 m thick, blue.

By way of navigation ice passability is estimated on a 10-point scale cohesion ice. The concentration (density) of ice is the ratio of the area of ​​ice floes and the gaps of water between them in a given area. The practice of ice navigation has shown that independent navigation of a conventional sea vessel is possible with a drifting ice concentration of 5-6 points.

According to dynamic ice is divided into fixed and floating.

Still ice exist in the form fast ice off the coast. The thickness of perennial fast ice off the coast of Greenland is more than 3 m, and off the coast of Antarctica tens and even hundreds of meters. The annual fast ice in the Arctic Ocean is about 2–3 m thick and up to 500 km wide (Laptev Sea).

floating ice is formed either by freezing of floating ice or as a result of breaking off from fast ice.

The term is used to refer to any type of floating sea ice. drift ice.

The sizes of drifting ice are different: with dimensions of more than 500 m in diameter, they are called icyfields, with dimensions 100…500m - fragments of icefields, with dimensions of 200…100m - large ice, with dimensions less than 20m - , finely broken ice.

The movement of ice occurs under the influence of wind or currents, under the influence of which they change their cohesion. With the wind blowing on the shore, the concentration of drifting ice increases, with the wind blowing from the shore, the ice is rarefied. With an increase in the speed of the currents, the ice is rarefied, with a decrease in the speed, the ice accumulates. Accumulation (compression) of ice occurs at the time of the change of tidal currents, and lasts 1-2 hours, after which the rarefaction of ice is observed. When the water level rises, the ice is rarefied, and when it falls, it coalesces.

Glacier ice - icebergs(ice mountains) are formed in areas of the Arctic Ocean and off the coast of Antarctica. They are carried by currents to the temperate latitudes of both hemispheres. Icebergs sometimes reach enormous sizes. In 1854, in the region of 44°S. 28°W.L. met an iceberg 120 km long and 90 m high. Only a tenth of the iceberg rises above the water.

Sea ice is ice formed in the sea (ocean) when water freezes. Since sea water is salty, freezing of water with a salinity equal to the average salinity of the oceans occurs at a temperature of about −1.8 ° C.

The assessment of the amount (density) of sea ice is given in points - from 0 (clear water) to 10 (solid ice).

Properties

The most important properties of sea ice are porosity and salinity, which determine its density (from 0.85 to 0.94 g/cm³). Due to the low density of ice, ice floes rise above the surface of the water by 1/7 - 1/10 of their thickness. The melting of sea ice begins at temperatures above −2.3°C. Compared to freshwater, it is more difficult to break into pieces and is more elastic. Salinity

The salinity of sea ice depends on the salinity of the water, the rate of ice formation, the intensity of water mixing and its age. On average, the salinity of ice is 4 times lower than the salinity of the water that formed it, ranging from 0 to 15 ppm (average 3 - 8 ‰).

Density

Sea ice is a complex physical body consisting of fresh ice crystals, brine, air bubbles and various impurities. The ratio of the components depends on the conditions of ice formation and subsequent ice processes and affects the average ice density.
Thus, the presence of air bubbles (porosity) significantly reduces the density of ice. The salinity of ice has less of an effect on density than does porosity. With an ice salinity of 2 ppm and zero porosity, the ice density is 922 kilograms per cubic meter, and with a porosity of 6 percent, it drops to 867.
At the same time, at zero porosity, an increase in salinity from 2 to 6 ppm leads to an increase in ice density only from 922 to 928 kilograms per cubic meter.

Thermophysical properties

The average thermal conductivity of sea ice is about five times higher than that of water, and eight times higher than that of snow, and is about 2.1 W / m °, but towards the lower and upper surfaces of the ice it may decrease due to an increase in salinity and an increase in the number of pores.

The heat capacity of sea ice approaches that of fresh ice as the temperature of the ice decreases as the salt brine freezes. With an increase in salinity, and, consequently, an increase in the mass of brine, the heat capacity of sea ice is increasingly dependent on the heat of phase transformations, that is, changes in temperature.
The effective heat capacity of ice increases with increasing salinity and temperature.

The heat of melting (and crystallization) of sea ice ranges from 150 to 397 kJ/kg, depending on temperature and salinity (with increasing temperature or salinity, the heat of melting decreases).

Optical properties

Pure ice is transparent to light rays. Inclusions (air bubbles, salt brine, dust) scatter the rays, significantly reducing the transparency of the ice.

Shades of color of sea ice in large massifs vary from white to brown.

White ice is formed from snow and has many air bubbles or brine cells.

Young sea ice with a granular texture with significant amounts of air and brine is often green in color.

Multi-year hummocky ice, from which impurities are squeezed out, and young ice that froze in calm conditions, often have a blue or blue color. Glacial ice and icebergs are also blue. In blue ice, the needle-like structure of crystals is clearly visible.

Brown or yellowish ice has a river or coastal origin, it contains impurities of clay or humic acids.

The initial types of ice (ice fat, sludge) have a dark gray color, sometimes with a steel tint. As the thickness of the ice increases, its color becomes lighter, gradually turning into white. When melting, thin pieces of ice turn gray again.

If the ice contains a large amount of mineral or organic impurities (plankton, eolian suspensions, bacteria), its color can change to red, pink, yellow, up to black.

Due to the property of ice to trap long-wave radiation, it is able to create a greenhouse effect, which leads to heating of the water under it.

Mechanical properties

Under the mechanical properties of ice understand its ability to resist deformation.

Typical types of ice deformation: tension, compression, shear, bending. There are three stages of ice deformation: elastic, elastic-plastic, and destruction stage.
Accounting for the mechanical properties of ice is important in determining the optimal course of icebreakers, as well as when placing cargo on ice floes, polar stations, and when calculating the strength of the ship's hull.

Conditions of education

When sea ice forms, tiny droplets of salt water are trapped between entirely fresh ice crystals, which gradually flow down. The freezing point and temperature of the greatest density of sea water depends on its salinity.
Sea water with a salinity below 24.695 ppm (so-called brackish water), when cooled, first reaches the highest density, like fresh water, and when further cooled and without agitation, it quickly reaches freezing point.
If the salinity of the water is higher than 24.695 ppm (salt water), it cools to the freezing point with a constant increase in density with continuous mixing (exchange between the upper cold and lower warmer layers of water), which does not create conditions for rapid cooling and freezing of water, that is, when Under the same weather conditions, salty ocean water freezes later than brackish water.

Classifications

Sea ice is divided into three types based on location and mobility:

floating (drifting) ice,

multi-year pack ice (pack).

According to the stages of ice development, several so-called initial types of ice are distinguished (in order of formation time):

ice needles,

ice fat,

intra-water (including bottom or anchor), formed at a certain depth and objects in the water under conditions of turbulent mixing of water.

Further in time of formation types of ice - nilas ice:

nilas, formed at a calm sea surface from lard and snow (dark nilas up to 5 cm thick, light nilas up to 10 cm thick) - a thin elastic crust of ice that easily bends on water or swell and forms jagged layers when compressed;

bottles formed in freshened water at a calm sea (mainly in bays, near river mouths) - a fragile, shiny crust of ice that easily breaks under the action of waves and wind;

pancake ice, which is formed during weak agitation from ice fat, snow or sludge, or as a result of a break as a result of the agitation of a bottle, nilas, or the so-called young ice. Represents rounded ice plates from 30 cm to 3 m in diameter and 10 - 15 cm thick with raised edges due to rubbing and impacts of ice floes.

The next stage in the development of ice formation is young ice, which is divided into gray (10-15 cm thick) and gray-white (15-30 cm thick) ice.

Sea ice that develops from young ice and is no more than one winter period old is called first-year ice.

This first-year ice can be:

thin one-year ice - white ice 30 - 70 cm thick,

medium thickness - 70 - 120 cm,

thick one-year ice - more than 120 cm thick.

If sea ice has been melted for at least one year, it is classified as old ice.

Old ice is divided into:

residual one-year - ice that has not melted in summer, which is again in the freezing stage,

two-year - lasted more than one year (thickness reaches 2 m),

multi-year - old ice with a thickness of 3 m or more, which has melted for at least two years. The surface of such ice is covered with numerous irregularities, mounds, formed as a result of repeated melting. The lower surface of multi-year ice is also characterized by great roughness and a variety of shapes.

The thickness of multi-year ice in the Arctic Ocean in some areas reaches 4 m.

In Antarctic waters, there is mainly first-year ice up to 1.5 m thick, which disappears in the summer.

According to the structure, sea ice is conditionally divided into acicular, spongy and granular, although it usually occurs in a mixed structure.

Distribution areas

According to the duration of the ice cover and its genesis, the water area of ​​the World Ocean is usually divided into six zones:

Water areas where ice cover is present all year round (the center of the Arctic, the northern regions of the seas of the Arctic Ocean, the Antarctic seas of Amundsen, Bellingshausen, Weddell.

Water areas where ice changes annually (Barents, Kara Seas).

Water areas with seasonal ice cover that forms in winter and completely disappears in summer (Azov, Aral, Baltic, White, Caspian, Okhotsk, Japan Seas).

Water areas where ice forms only in very cold winters (Marmara, North, Black Seas).

Water areas where ice is observed brought by currents from their borders (Greenland Sea, Newfoundland region, a significant part of the Southern Ocean, including the area where icebergs are distributed.

The rest of the water areas that make up most of the World Ocean, on the surface of which there is no ice.

Bottom ice

Bottom ice - an accumulation of masses of ice of a loose spongy structure at the bottom of natural watercourses, usually before the onset of ice drift.

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See what "Bottom Ice" is in other dictionaries:

BOTTOM, bottom, bottom (special). adj. to the bottom. Bottom ice (settled to the bottom). Bottom fishing rod (attached so that the line with a hook reaches the bottom). Explanatory Dictionary of Ushakov. D.N. Ushakov. 1935 1940 ... Explanatory Dictionary of Ushakov

Ground, grassroots Dictionary of Russian synonyms. bottom adj., number of synonyms: 2 ground (4) ... Synonym dictionary

See bottom. Explanatory dictionary of Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov

Accumulations of intra-water ice (See. Intra-water ice) at the bottom of non-freezing sections (polynyas) of rivers and lakes ... Great Soviet Encyclopedia

I adj. 1. ratio with noun. bottom I, associated with it 2. Peculiar to the bottom [bottom I], characteristic of it. 3. Living, growing, located at the bottom [bottom I 1.] or at the very bottom of the reservoir. II adj. 1. ratio with noun. sweet clover associated with it 2.… … Modern explanatory dictionary of the Russian language Efremova