Icebergs are giant floating mountains of ice. various shapes, broken off from glaciers covering continents.

1. Melting glaciers. Glaciers of the Himalayas.

Glaciers are natural formations that represent accumulations of ice of atmospheric origin. On the surface of our planet, glaciers occupy more than 16 million km 2, that is, about 11% of the total land area, and their total volume reaches 30 million km 3.

More than 99% of the total area of ​​the Earth's glaciers belongs to the polar regions. However, glaciers can be seen even near the equator, but they are located on the peaks high mountains. For example, the highest peak in Africa - Mount Kilimanjaro - is topped by a glacier, which is located at least 4500 m.

An area where snow accumulates and does not have time to melt completely. summer period- glacier feeding area. This is where the glacier is born from the snow.
In the area of ​​nutrition, snow turns to ice in various ways. First, the crystals become larger and the space between them decreases. This is how firn is formed - transition state from snow to ice. Further compaction under the pressure of the overlying snow leads to the formation of milky white ice (due to numerous air bubbles).

2. A giant glacier split in Greenland.

Glaciers tend to flow, revealing plastic properties. In this case, one or more glacier tongues are formed. The speed of glacier movement reaches several hundred meters per year, but it does not remain constant. Since the plasticity of ice depends on temperature, the glacier moves faster in summer than in winter. Glacial tongues resemble rivers: precipitation collects in a channel and flows along the slopes.

Northern icebergs break away from the Greenland Ice Sheet. It throws more than 300 km 2 of ice into the ocean every year. Northern icebergs are smaller in size than southern, Antarctic icebergs. Most often, northern icebergs are 1-2 km long, but there are also those that reach 200 and even 300 km in length and more than 70 km in width. The height of individual ice mountains together with the underwater part can reach 600 m.

The cruising range of icebergs and the duration of their existence depend not only on the speed and direction of sea currents, but also on the properties of the iceberg itself. Very large and deeply frozen (up to -60°C) Antarctic icebergs exist for many years, and sometimes for more than a decade.

Greenland icebergs melt faster - in just 2-3 years. They are smaller, and their freezing temperature is not lower than -30°C.
Depending on their origin, icebergs also differ in their shape. Greenland icebergs are dome-shaped ice mountains, less often they have a pyramidal shape. Antarctic icebergs most often have a flat surface and vertical vertical walls.

3.

Table-shaped icebergs are characterized by flat, relatively smooth tops and huge sizes and are formed as a result of breaking off ice shelves. They consist of ice at various stages of formation - from compressed snow - firn, to solid glacier ice. The density of the main mass of the iceberg is from 0.5 to 0.8 g/cubic. cm, which provides it with good buoyancy even with a significant depth of the underwater part.

The color of icebergs is constantly changing: the newly calved ice mass has a dull white color due to the high air content in the upper layers of young firn ice. Gradually, air bubbles are replaced by drops of water, and the color acquires a delicate bluish tint.

Table-shaped icebergs can reach colossal sizes. In 1956, the icebreaker Glacier near Scott Island encountered an iceberg 385 kilometers long and 111 kilometers wide, which drifted in the ocean for many years - in 1959 it was discovered by the whaling ship Slava.

Ice giants are not uncommon - in December 1965, ice reconnaissance discovered an ice island with an area of ​​about 7,000 square kilometers. In general, table-shaped icebergs are significantly smaller than the record holders: average length equal to 580 meters, the average height of the surface part is 28 meters, under water there is more than a hundred meters of ice block.

4.

Pyramid icebergs are formed as a result of long tongue glaciers sliding into the ocean; they have a pointed top and a high surface area. Their dimensions are relatively small: the average length is about 130 meters, height - 54 meters.

In 1904, the Zenit ship in the Falkland Islands encountered an iceberg 450 meters high; there were also higher pyramidal blocks.
They usually have a soft greenish or bluish tint, but dark icebergs are also found. An ice block contains a large amount of rock fragments, silt and sand, absorbed by the glacier as it moves over land.

In 1773, the first press report appeared about black icebergs off the coast of Antarctica. Scientists have suggested that the black color of icebergs is caused by the activity of volcanoes in the Southern Shetland Islands. The glaciers on these islands are covered with a thick layer of volcanic dust, which is not washed off even by sea water.

5.

Icebergs from the northern and southern hemispheres pose a serious threat to navigation. The icy mountains of the North Atlantic are especially dangerous, which even on clear nights are visible from a distance of no more than 500 - 600 meters. At such a distance, the ship can no longer avoid a collision, even when working “full backwards”.

In this area, the cold Labrador Current meets the warm waters of the Gulf Stream, which creates dense and long-lasting fogs in which the iceberg can be spotted from the bridge of a ship just minutes before the collision. Dozens of ships became victims of ice wanderers, thousands of people died.

6.

Icebergs float to about 40 latitudes in the Northern and Southern Hemispheres and end up in areas of heavy shipping, which they pose a threat to. The danger lies in the fact that, firstly, ice reflects the sun's rays, cools the air and contributes to the formation of fog; secondly, most of the iceberg (up to 90% of its volume) is under water.

Ship collisions usually occur with the invisible part of the iceberg.
The world was shocked by the death of the Titanic in April 1912, which, having avoided a direct collision with the iceberg, only slid starboard along its underwater part - two hours later only a few overcrowded boats remained on the surface of the ocean.
Of particular danger are old, melted icebergs, which cannot be detected at all when the sea is rough. It was this iceberg that caused the Titanic disaster.

7. Titanic

In 1913, thirteen major maritime powers signed an agreement to create the International Ice Patrol, centered in Newfoundland. It maintains contact with ships and aircraft in the patrol area, analyzes data
observations and ensures timely notification of all vessels about detected icebergs.

Watching the movement of icebergs is quite difficult task, since it is very difficult to predict in which direction and at what speed the ice giant will move. To facilitate observation, the iceberg is marked with bright paint or an automatic radio beacon is dropped onto its surface.
Good results provide observational data obtained from space satellites.
Now ships are equipped with special devices that warn of icebergs.

The measures taken gave tangible results - disasters practically stopped, but on January 30, 1959, the Danish cargo and passenger ship Hans Hedhovt with a displacement of 3,000 tons collided with an iceberg and lost all its passengers and crew. True, the collision occurred outside the patrol area. The complete safety of ships in areas where icebergs occur cannot be guaranteed, so navigators on duty on the navigation bridge must exercise special care.

Swimming close to an iceberg is also dangerous - a melted iceberg's center of gravity shifts upward, it is in a state of unstable equilibrium and can capsize at any moment. The capsizing of the iceberg was observed from the board of the motor ship “Ob” in the Davis Sea, and eyewitnesses described the event as follows: “ In calm weather, a strong roar was heard, comparable in strength to an artillery salvo. Those on deck saw, at a distance of no more than one kilometer from the ship, a slowly overturning pyramidal iceberg about forty meters high. Huge blocks of ice broke off from its surface and fell into the water with a roar. When the surface part of the iceberg noisily sank into the water, a rather large swell began to emanate from it, causing the ship to rock. On the surface of the sea, among the debris, a new hilly and uneven iceberg tip slowly swayed».

8.

The edge of the iceberg may collapse, which also threatens the ship with serious consequences. The position of a ship trapped in ice is especially dangerous.
An iceberg, moving under the influence of an underwater current, crushes ice fields and, approaching a ship, can crush it.
Of the various projects for destroying icebergs, not a single one has been implemented: bombing is perceived by the ice giant as needle pricks, and to melt millions of tons of ice will require a fantastic amount of energy.

9.

But icebergs can also serve as a source of fresh water, which people are increasingly lacking. Projects are already being developed to “catch” and tow icebergs to waterless areas of the Earth. The initiator of the first conference to discuss the problem of using icebergs was the king of Saudi Arabia, a country located in the desert.

IN recent years Many areas of Africa and Australia are experiencing an acute shortage of fresh water. That’s why a project arose to tow individual icebergs to the shores South Africa and Australia and the use of water generated by their melting for industrial and other
goals. It is estimated that one medium-sized iceberg can produce an amount of clean fresh water that can be compared to the flow of a large river.

IN southern latitudes oceans, in the areas of the “roaring forties”, the ship does not even have anywhere to hide from storm winds and waves - for hundreds of miles around you will not find a single island. Huge ice icebergs can become a reliable protection - on the leeward side you can wait out the storm and carry out transshipment operations from ship to ship. And the flat area of ​​table-shaped icebergs can be used as a runway for light aircraft.
But when performing these operations, one must constantly remember the insidious nature of icebergs, which at any moment can turn into a dangerous enemy.

The famous "Calypso" by Jacques-Yves Cousteau was heading to Antarctica for oceanographic and meteorological observations.

10. "Calypso"

Hundreds of ice blocks surrounded the small ship, and then troubles began: first one propeller failed, then the axis of the second propeller broke and the ship lost control. The wind and waves drove the Calypso towards the foot of a giant iceberg, which was tilting suspiciously. Ice fragments rained down onto the deck of the ship, and the next wave of the Calypso hit the side of the iceberg - a one and a half meter hole was formed, but, fortunately, it ended up above the waterline.
Only improved weather saved the ship from destruction; it barely made it to the nearest island, from where it was towed to a South American harbor.

Introduction
Iceberg Definition
Main geographical location
Examples from history
Iceberg Advantage
Literature

Icebergs
There are huge ice mountains in the sea - fragments of ice from polar glaciers. They are called icebergs ; translated from German “Eisberg” this means “ice mountain” (“ice” - ice and “berg” - mountain, “ice mountain”).
Icebergs are huge masses of ice that slide into the ocean from a continent or island in the form of glacial tongues or break off from the icy shores surrounding Greenland and Antarctica in a powerful ring. The northern homeland of icebergs is Greenland, which continuously accumulates ice on its surface and then dumps the excess into the waters of the Atlantic. From here they, driven by winds and currents, begin their journey to the south, across the sea routes connecting the two continents. The depth of the raids depends on the time of year: in March they descend no lower than 50° north latitude, and in October they can reach 40° north latitude, where many transoceanic routes lie (see figure).
Icebergs form where there are glaciers descending from mountains into the sea. Such glaciers lie in mountainous areas of the polar countries and are large, tens or hundreds of meters thick, masses of pure ice. The ice mass of the glacier only seems impossibly movable. In fact, the ice is sliding down the mountainside all the time. Having reached the shore, the glacier enters the sea. At first, not far from the shore, the ice continues to crawl along the bottom, but then, as it moves away from the shore, it floats on the surface of the sea. Wave impacts gradually destroy the edge of the glacier. Longitudinal cracks appear, which, growing larger, break off part of the ice. In a terrible roar, like the shots of a hundred artillery guns, an iceberg is born. A huge mass of ice breaks off from the edge of the glacier and collapses into the sea. One by one, the icebergs float further out to sea, driven by the current and wind. Among them there are giants with a height of almost 200 meters and an area of ​​more than a square kilometer!
If an ice mountain runs aground, it will be stuck here for a long time, forming a kind of ice island.
The second, southern homeland of icebergs sends them sailing to the fortieth latitude of all three oceans:

Quiet,
Indian
and Atlantic.

True, these areas are crossed much less frequently by ships, since the main trade routes pass through the Suez and Panama Canals. Number and size of icebergs in southern hemisphere incomparably more than in the north.
Table-shaped icebergs are characterized by flat, relatively smooth tops and huge sizes and are formed as a result of breaking off ice shelves. They consist of ice at various stages of formation - from compressed snow - firn, to solid glacier ice. The density of the main mass of the iceberg is from 0.5 to 0.8 g/cubic. cm, which provides it with good buoyancy even with a significant depth of the underwater part. The color of icebergs is constantly changing: the newly calved ice mass has a dull white color due to the high air content in the upper layers of young firn ice. Gradually, air bubbles are replaced by drops of water, and the color acquires a delicate bluish tint.
Table-shaped icebergs can reach colossal sizes. In 1956, the icebreaker Glacier near Scott Island encountered an iceberg 385 kilometers long and 111 kilometers wide, which drifted in the ocean for many years - in 1959 it was discovered by the whaling ship Slava. Ice giants are not uncommon - in December 1965, ice reconnaissance discovered an ice island with an area of ​​​​about 7,000 square kilometers. In general, table-shaped icebergs are significantly smaller than the record holders: the average length is 580 meters, the average height of the surface part is 28 meters, and there is more than a hundred meters of ice block under water (see figure).
Pyramid icebergs are formed as a result of long tongue glaciers sliding into the ocean; they have a pointed top and a high surface area. Their dimensions are relatively small: the average length is about 130 meters, height - 54 meters. In 1904, the Zenit ship in the Falkland Islands encountered an iceberg 450 meters high; there were also higher pyramidal blocks. They usually have a soft greenish or bluish tint, but dark icebergs are also found. An ice block contains a large amount of rock fragments, silt and sand, absorbed by the glacier as it moves over land.
Icebergs from the northern and southern hemispheres pose a serious threat to navigation. The icy mountains of the North Atlantic are especially dangerous, which even on clear nights are visible from a distance of no more than 500 - 600 meters. At such a distance, the ship can no longer avoid a collision, even when working “full backwards”. In this area, the cold Labrador Current meets the warm waters of the Gulf Stream, which creates thick and long-lasting fogs in which the iceberg can be detected from the bridge of a ship just minutes before the collision. Dozens of ships became victims of ice wanderers, thousands of people died. The world was shocked by the death of the Titanic in April 1912, which, having avoided a direct collision with the iceberg, only slid starboard along its underwater part - two hours later only a few overcrowded boats remained on the surface of the ocean.
In 1913, thirteen major maritime powers signed an agreement to create the International Ice Patrol, centered in Newfoundland. It communicates with ships and aircraft in the patrol area, analyzes observation data and ensures timely notification of all ships about detected icebergs. Observing the movement of icebergs is a rather difficult task, since it is very difficult to predict in which direction and at what speed the ice mass will move. To facilitate observation, the iceberg is marked with bright paint or an automatic radio beacon is dropped onto its surface. Good results are obtained from observational data obtained from space satellites.
The measures taken gave tangible results - disasters practically stopped, but on January 30
In 1959, the Danish cargo-passenger ship Hans Hedhovt with a displacement of 3,000 tons collided with an iceberg and perished along with all passengers and crew. True, the collision occurred outside the patrol area. The complete safety of ships in areas where icebergs occur cannot be guaranteed, so navigators on duty on the navigation bridge must exercise special care.
Swimming close to an iceberg is also dangerous - a melted iceberg's center of gravity shifts upward, it is in a state of unstable equilibrium and can capsize at any moment. The capsizing of the iceberg was observed from the board of the motor ship “Ob” in the Davis Sea, and eyewitnesses described the event as follows: “In calm weather, a strong roar was heard, comparable in strength to an artillery salvo. Those on deck saw, at a distance of no more than one kilometer from the ship, a slowly overturning pyramidal iceberg about forty meters high. Huge blocks of ice broke off from its surface and fell into the water with a roar. When the surface part of the iceberg noisily sank into the water, a rather large swell began to emanate from it, causing the ship to rock. On the surface of the sea, among the debris, a new hilly and uneven top of the iceberg slowly swayed.
The edge of the iceberg may collapse, which also threatens the ship with serious consequences. The position of a ship trapped in ice is especially dangerous. An iceberg, moving under the influence of an underwater current, crushes ice fields and, approaching a ship, can crush it.
Of the various projects for destroying icebergs, not a single one has been implemented: bombing is perceived by the ice giant as needle pricks, and to melt millions of tons of ice will require a fantastic amount of energy.
In recent years, many areas of Africa and Australia have experienced an acute shortage of fresh water. Therefore, a project arose to tow individual icebergs to the shores of South Africa and Australia and use the water generated by their melting for industrial and other purposes. It is estimated that one medium-sized iceberg can produce an amount of clean fresh water that can be compared to the flow of a large river.
In the southern latitudes of the oceans, in the areas of the “Roaring Forties”, the ship has nowhere to hide from stormy winds and waves - for hundreds of miles around you will not find a single island. Huge ice icebergs can become a reliable protection - on the leeward side you can wait out the storm and carry out transshipment operations from ship to ship. And the flat area of ​​table-shaped icebergs can be used as a runway for light aircraft.
But when performing these operations, one must constantly remember the insidious nature of icebergs, which at any moment can turn into a dangerous enemy.
The famous "Calypso" by Jacques-Yves Cousteau was heading to Antarctica for oceanographic and meteorological observations. Hundreds of ice blocks surrounded the small ship, and then troubles began: first one propeller failed, then the axis of the second propeller broke - the ship lost control. The wind and waves drove the Calypso towards the foot of a giant iceberg, which was tilting suspiciously. Ice fragments rained down onto the deck of the ship, and the next wave of the Calypso hit the iceberg on its side - a one and a half meter hole was formed, but, fortunately, it ended up above the waterline. Only improved weather saved the ship from destruction; it barely made it to the nearest island, from where it was towed to a South American harbor.
Iceberg - a large, free-floating piece of ice in the ocean or sea. Typically, icebergs break off from ice shelves. The nature of icebergs was first correctly explained by the Russian scientist Mikhail Lomonosov. Since the density of ice is 920 kg/m² and the density of sea water is about 1025 kg/m³, about 90% of the iceberg's volume is under water.
In 2000, the largest currently known iceberg, B-15, with an area of ​​over 10,000 km2, broke off from the Ross Ice Shelf as a result of mechanical ablation. In the spring of 2005, its fragment - iceberg B-15A - had a length of more than 115 kilometers and an area of ​​more than 2500 km? and was still the largest iceberg observed.
The Ross Ice Shelf iceberg, named B7B, measuring 19 by 8 kilometers (an area larger than Hong Kong) was spotted in early 2010 by NASA and ESA satellite imagery about 1,700 kilometers south of Australia. The original size of this iceberg was about 400 square kilometers. Icebergs of this size and so far from their source of origin have not been observed in the last hundred years. It took iceberg B7B about 10 years to float this far north. The coordinates of iceberg B7B at the beginning of 2010 are 48.8° S. w. 107.5° E. d. (G) (O).
If the iceberg is blue, it is likely over 1000 years old. The dark blue color is the so-called. “black” icebergs that have recently capsized in the water.
The construction of inhabited research bases is practiced on icebergs. It is already sometimes practiced to tow icebergs to dry areas.
Our Earth is called the blue planet. And not by chance. After all, 70% of the earth's surface is water. Water exists not only in liquid, but also in solid state (at negative temperatures). Solid water is ice, glaciers that make up the Earth's ice shell. Glaciers are perennial masses of ice formed by the accumulation and transformation of snow, which move under the influence of gravity and take the form of streams, convex sheets or floating slabs (ice shelves). Polar glaciers almost always reach the oceans and seas and actively interact with them, which is why they are called “marine”. Glaciers can invade cold, shallow seas, moving onto the continental shelf. The ice sinks into the water, which leads to the formation of ice shelves - floating slabs consisting of firn (compressed porous snow) and ice. Icebergs periodically break off from them. At contact with the sea, the movement of ice streams accelerates, their ends float up, forming floating tongues, which also become the source of a huge number of icebergs. We will talk about icebergs in our work.
The end of the glacier hangs over the sea for some time. It is undermined by tides, sea currents, and winds. Finally it breaks off and falls into the water with a crash. Every year, ice streams form tens of cubic kilometers of ice per year. All Greenland glaciers annually throw out more than 300 km 3 of ice into the ocean, ice streams and ice shelves of Antarctica - at least 2 thousand km 3.
Greenland icebergs are often real ice mountains with a dome-shaped or pyramidal shape. They can rise above the water by 70 - 100 m, which is no more than 20-30% of their volume, the remaining 70-80% is hidden under water. With the East Greenland and Labrador Currents, iceberg masses are carried up to 40-50 0 north latitude, in some cases even further south.
In Antarctic waters, icebergs served the Yuri Dolgoruky whaling flotilla well. Severe storms prevented sailors from reloading finished products onto a refrigerator and taking fuel from a tanker. And then the sailors saw two icebergs nearby. There were high waves all around, and between them there was only a slight swell. The sailors risked standing between the icebergs and, under their protection, performing the necessary overload. This seems to be the only time icebergs helped the sailors. But icebergs are not only a majestic natural phenomenon. They can serve as a source of fresh water, which is increasingly scarce for people. Projects are already being developed to “catch” and tow icebergs to waterless areas such as Saudi Arabia and South-West Africa.
Any creation of nature is unique and inimitable. Ice mountains in the ocean are an unforgettably beautiful and majestic picture. They have the most bizarre shapes and are amazingly colored. They resemble giant crystals of precious stones: bright green, dark blue, turquoise. This is how the sun's rays are refracted in perfectly clean polar ice floes saturated with air bubbles. Because of these bubbles, which are much lighter than water, icebergs are immersed in water only five-sixths of their volume.
The true size of icebergs far exceeds imagination. In the Arctic, these mountains of ice rise above sea level by an average of 70 m, sometimes reaching a height of 190 m, and the length of some of them reaches several kilometers. The drifting station “North Pole - 6” and the first American Arctic stations in the Arctic Ocean operated on such ice islands. The flat-topped masses of Antarctic icebergs have an average surface height of 100 m, and some of them rise above the water by 500 m and have a length of 100 km or more.
Sea currents and winds pick up icebergs and carry them from the polar seas to the ocean. In the Southern Hemisphere, large Antarctic icebergs penetrate particularly far into the Atlantic Ocean, here they reach 26 0southern latitude, i.e. up to the latitude of Rio de Janeiro, in the Pacific and Indian oceans, icebergs do not float north of 50-40 0 south latitude.
In the Northern Hemisphere, especially many Arctic icebergs are carried by the East Greenland and Labrador currents into the Atlantic Ocean, where they reach the latitude of England. And here, on the routes of busy transatlantic shipping, they pose a serious threat to ships. But modern ships are equipped with sophisticated instruments that warn at a great distance of the approach of any obstacle, including icebergs.
With the help of icebergs, as we have already said, it would be possible to solve the problems of supplying the arid regions of the Earth with fresh water. The famous American oceanographer and engineer John Isaacs came up with a tempting idea - to tow a large iceberg to the shores of water-stricken California, and use the water generated when the iceberg melts to irrigate dry lands. It can be assumed that the colossal mass of ice, which will melt very slowly even in the hot Californian climate, can cause increased condensation of atmospheric moisture and additional precipitation. This will lead to an increase in water reserves in the reservoir and a slight decrease in the dry climate on the coastline adjacent to the iceberg. This could be used in other arid areas of the world, most notably in Australia.
Like any natural phenomenon, icebergs require careful study by scientists so that they can benefit humans without disturbing the balance in nature.

Literature used

E. Bauer. Wonders of the Earth. M., "Children's Literature", 1978
Encyclopedia for children. Geography. M., “Avanta +”, 1994
Popular maritime encyclopedia - Yu.G. Glotov and V.A. Semchenko
etc.............

An iceberg is a huge mass of ice that slides off a continent or island into the ocean or breaks off from the shore. This word is translated as Their existence was first reliably explained by M. Lomonosov. Due to the fact that approximately 10% less the main part of the iceberg (up to 90%) is hidden below the water surface.

Where do icebergs form?

In the northern hemisphere, their birthplace is Greenland, which constantly accumulates layers of ice and, from time to time, sends the excess into the Atlantic Ocean. Under the influence of currents and winds, ice blocks are sent to the south, crossing sea ​​routes, which connect North and South America with Europe. The length of their journey differs in different seasons. In spring they do not even reach 50º C. las., and in the fall they can reach 40º C. w. Transoceanic sea routes pass at this latitude.

An iceberg is a block of ice that can form off the coast of Antarctica. From this place their journey to the forties latitudes of the Pacific, Atlantic and Indian Oceans begins. These areas are not so in demand among sea carriers, because their main routes go through Panama and However, the dimensions of icebergs and their number here far exceed those in the northern hemisphere.

Table-shaped icebergs

Having learned what an iceberg is, you can consider their varieties. Table-shaped ice floes are the result of the calving process large areas ice shelves. Their structure can be very different: from firn to glacier ice. The color characteristics of an iceberg are not constant. Freshly chipped snow has a white matte tint due to the large proportion of air in the outer layer of compressed snow. Over time, the gas is displaced by droplets of water, causing the iceberg to turn light blue.

A table iceberg is a very massive block of ice. One of the largest representatives of this type had dimensions of 385 × 111 km. Another record holder had an area of ​​about 7 thousand km 2. The majority of table-shaped icebergs are orders of magnitude smaller than those indicated. Their length is about 580 m, height from the water surface is 28 m. On the surface of some, rivers and lakes with melt water can form.

Pyramid icebergs

The pyramidal iceberg is the result of ice landslides. They are distinguished by a peak with a sharp end and a significant height above the surface of the water. The length of ice blocks of this type is about 130 m, and the height of the surface part is 54 m. Their color differs from table-shaped ones in a soft greenish-bluish tint, but darker icebergs have also been recorded. The thickness of the ice contains significant inclusions of rocks, sand or silt, which fell into it while moving across the island or mainland.

Threat to seagoing vessels

Icebergs located in the northern part are considered the most dangerous. Atlantic Ocean. Every year, up to 18 thousand new ice bodies are recorded in the ocean. They can only be seen from a distance of no more than half a kilometer. This is not enough time to turn away or stop the ship to prevent a collision. The peculiarity of these waters is that there is often a thick fog that does not dissipate for a long time.

Sailors are familiar with the terrible meaning of the word "iceberg". The most dangerous are old ice floes that have melted significantly and barely protrude above the ocean surface. In 1913, the International Ice Patrol was organized. Its employees are in contact with ships and aircraft, collecting information about icebergs and warning of danger. It is almost impossible to predict the movement. To make them more visible, icebergs are marked with bright paint or an automatic radio beacon.

11. Ice in the ocean.

© Vladimir Kalanov,
"Knowledge is power."

Ice is the solid phase of water, one of its aggregate states. Pure fresh water freezes at a temperature almost equal to zero (below zero by only 0.01-0.02 ° C). At the same time, water that has been purified in laboratory conditions to the maximum possible extent and is in a calm state can be cooled without forming ice to a temperature of minus 33°C. But the smallest piece of ice or other tiny object placed in such supercooled water will instantly cause rapid ice formation.

Normal ocean water, with a salinity of 35‰, freezes at minus 1.91°C. At a salinity of 25 ‰ (White Sea) water freezes at a temperature of minus 1.42°C, at a salinity of 20 ‰ (Black Sea) - at minus 1.07°C, and in the Sea of ​​Azov (salinity 10 ‰) surface water freezes at a temperature minus 0.53°C.

Freezing fresh water does not change its composition. The situation is different when sea water freezes. Freezing begins with the formation of thin, elongated ice crystals, which contain absolutely no salt. Gradually, when the lumps of these crystals begin to freeze, salt gets into the ice.

The salinity of sea ice, i.e. The salinity of the water formed when it melts is on average about 10% of the salinity of ocean water. Over time, this figure decreases, and multi-year ice can be almost fresh.

The volume of ice is 9 percent greater than the volume of water from which it was formed, because... V crystal lattice Ice packing of water molecules is ordered and becomes less dense. Therefore, the density of sea ice is less than the density of sea water and ranges from 0.85-0.94 g/cm 3 . That is why floating ice rises above the surface of the water by 1/7 - 1/10 of its thickness.

Strength sea ​​ice noticeably lower than freshwater, but it increases with decreasing temperature and salinity of ice. Multi-year ice has the greatest strength.

Ice 60 cm thick, which forms on freshwater bodies in the depths of winter, can withstand a load of up to 15-18 tons, if, of course, this load is not applied concentratedly, but in the form of, say, a cargo platform on a caterpillar track, the supporting surface of which is approximately 2 .5 m2.

At this point we will make a small digression, but not at all lyrical. Lake Ladoga, as is known, has only a weak connection with the oceans and ocean ice. But we want to remind you that in 1941-1942 the ice “Road of Life” was laid along this lake, which saved the lives of many tens of thousands of people. Our young readers should definitely become familiar with the heroic and dramatic history of the construction and operation of this legendary road of life.

In the oceans, ice forms in high and temperate latitudes. In the polar regions, ice remains for several years. This perennial, so-called pack ice reaches its greatest thickness in the central regions of the Arctic Ocean - up to 5 meters. Sea ice begins to melt when its temperature exceeds minus 23°C. In the Arctic in summer, the thickness of ice due to the melting of its upper layers can decrease by 0.5-1.0 meters, but over the winter up to 3 meters of ice can freeze below. This multi-year ice is gradually carried by currents to temperate latitudes, where it melts relatively quickly. It is believed that the lifespan of Arctic ice that forms off the coast of Russia ranges from 2 to 9 years, and Antarctic ice lasts even longer. The ice cover in the oceans reaches its greatest extent at the end of winter: in the Arctic it covers an area of ​​about 11 million km 2 by April, and about 20 million km 2 in the Antarctic by September. If we talk about permanent ice cover , then it makes up 3-4 percent of the total area of ​​the World Ocean.

Ice cover may consist not only of fast ice, i.e. motionless ice frozen to the shore, but also moving drifting ice With a strong wind coinciding in direction with the sea current, drifting ice can travel a distance of up to 100 km per day.

Falling snow often creates large drifts on the ice. The snow gradually freezes, increasing the thickness of the ice cover. Sometimes hurricane-force winds break the ice, creating high hummocks. On such ice, if we talk about the Arctic, only polar bear, and even then with great difficulty.

But the ocean also contains ice that formed on land. These are so-called icebergs - huge blocks of fresh ice.(German Eisberg - ice mountain). Icebergs are delivered to the ocean by continental glaciers at polar latitudes. The largest ice sheet on Earth is located in Antarctica. Its area is 13.98 million km 2, i.e. 1.5 times the area of ​​Australia. At the same time, the area of ​​the continent of Antarctica itself is estimated at 12.09 million km 2. the rest is accounted for by the ice that covers almost the entire shelf of Antarctica. Average thickness Antarctic ice is 2.2 km, and the largest is 4.7 km. The volume of ice is estimated at 26 million cubic kilometers. The enormous weight of ice pressed this continent into earth's crust. As a result, much of Antarctica's surface lies below sea level. The Antarctic glacier annually receives 2000-2200 km 3 of ice from snow and loses about the same amount to icebergs. Of course, this balance cannot be accurately calculated. Therefore, the scientific world does not yet have a clear answer to the question of whether the Antarctic glacier is increasing or decreasing.

Icebergs in the form of huge blocks, similar to mountains, slowly slide from the mainland into the sea, and then crash into the water with a roar. In Antarctica, the largest volume of ice in the form of icebergs is provided by two giant ice shelves advancing into the Ross and Weddell Seas. For example, the Ross Ice Shelf has an area exceeding 500 thousand km 2, and the ice thickness here reaches 700 meters. In the Ross Sea, this glacier approaches in the form of a huge ice barrier almost 900 km long and up to 50 meters high.

There are about 100 thousand icebergs constantly floating around Antarctica. Comprehensive monitoring, including monitoring of icebergs, is carried out by 35 people working here scientific stations from different countries. Russia has 8 scientific stations here, the USA - 3, Great Britain - 2. Ukraine, Poland, Argentina and other countries also have Antarctic scientific stations.

The international legal regime of Antarctica and other territories located south of 60° S is regulated by the Antarctic Treaty of December 1, 1959.

In the Northern Hemisphere, the main supplier of icebergs to the ocean is Greenland. It is believed that up to 15 thousand huge pieces of ice break off from the glaciers of this island every year. From here they sail into one of the busiest areas of the Atlantic Ocean.

Icebergs also break off from the glaciers of the islands of the Arctic Ocean - Franz Josef Land, Novaya Zemlya, Severnaya Zemlya, Spitsbergen and the Canadian Arctic Archipelago.

In general, glaciers occupy 16.1 million km 2 of land, of which 14.4 million km 2 are covered by ice sheets (85.3% in Antarctica, 12.1% in Greenland). In terms of area and volume of water, glaciers occupy second place on Earth after the World Ocean, and in terms of fresh water content they surpass all rivers, lakes and groundwater, taken together.

Icebergs are table-shaped and pyramidal in shape. The table-shaped shape is characteristic of Antarctic icebergs, which are formed when they are separated from a huge mass of ice of a homogeneous structure. When glaciers move relatively quickly, the shape of the broken pieces often resembles a pyramid. As the underwater and surface parts melt unevenly, icebergs take on various, most bizarre shapes, and with loss of stability they can capsize.

Icebergs can reach enormous sizes. Especially large icebergs form from the ice shelves of Antarctica. In 1987, with the help of Earth satellites, an iceberg 153 km long and 36 km wide was discovered in the Ross Sea area.

An iceberg called B-15 broke off from the same glacier in 2000. This giant had an area of ​​more than 11,000 km 2. If an ice floe of such an area ended up on Lake Ladoga, it would cover 63% of the surface of this large (17.7 thousand km 2) lake.

The mass of such giants can amount to hundreds of millions and even billions of tons. But this is clean fresh water, the shortage of which has long been felt by many countries.

The heat capacity of ice melting is very high. It takes 80 calories to melt 1 gram of ice, not including the heat it takes to warm the ice to zero degrees. It is no coincidence that projects for towing icebergs to the shores of such coastal states as Japan, Saudi Arabia, Kuwait, and the United Arab Emirates have long arisen. Calculations show that the iceberg is of “medium” size: 1 km long, 600 m wide and a total height of 300 m during the towing journey, for example, from Antarctica to Saudi Arabia will lose no more than 20% of its volume. The initial weight of such an iceberg would be about 180 million tons (in water it is much less). If towing an iceberg of this size remains a technically difficult task, then the delivery of relatively small ice fragments with a volume of 200-300 thousand cubic meters is quite doable and is already carried out from time to time by the countries mentioned above.

Having broken off from glaciers, icebergs, picked up by currents and driven by winds, sometimes float far beyond the polar regions. Antarctic icebergs reach the southern coast of Australia, South America and even Africa. Icebergs from Greenland penetrate into the North Atlantic up to forty degrees north latitude, i.e. latitudes of New York, and sometimes further south, reaching the Azores and even Bermuda.

The cruising range of icebergs and the time of their existence in the ocean depend not only on the direction and speed of sea currents, but also on the physical properties of the icebergs themselves. Very large and deeply frozen (down to minus 60 degrees) Antarctic icebergs exist for several years, and in some cases even decades.

Greenland icebergs melt much faster, in just 2-3 years, because... they are not so large in size and their freezing temperature is no more than minus 30 degrees.

It is unnecessary to explain what danger floating ice mountains pose for shipping. More than once collisions with icebergs have led to disasters at sea. But none of these disasters can compare with the tragedy that took place at the beginning of the 20th century in the North Atlantic.

Nowadays, the danger of colliding with icebergs has decreased significantly compared to the times of the Titanic. Quite reliable radar and other equipment is installed on sea vessels, in ports, and on artificial earth satellites to monitor, alert and warn about the danger of encountering icebergs. In the North Atlantic, where there are busy sea routes, a special ice patrol . It warns ship captains about the locations of large icebergs. The International Ice Patrol includes 16 countries. His ships detect icebergs, warn about the location of icebergs and the direction of their movement. The functions of the ice patrol also include the fight against icebergs, which is carried out with the help of explosions, the use of incendiary bombs, dark coloring of ice blocks, for example, by applying a layer of soot to the surface of the iceberg to speed up the melting process, etc.

However, the measures taken cannot be exhaustive. Icebergs appear in the ocean according to the laws of nature. No one can completely guarantee sea vessels against ice danger. The ocean is large and often fraught with dangers, for which it is always necessary to prepare in advance.

© Vladimir Kalanov,
"Knowledge is power"

The journal Geophysical Research published research on the reasons influencing the movements of icebergs. Scientists have now been able to model the drift of Antarctic icebergs across the Southern Ocean, as well as determine the factors underlying their movement and melting.
Scientists from all over the world are closely monitoring the Larsen Ice Shelf off the coast of the Antarctic Peninsula. A massive iceberg began to break off from the glacier. The future block of ice is approximately 175 km long and 50 km wide. Its total area can be 6 thousand square meters. km, and the weight is 1300 gigatons, which is comparable to the weight of all icebergs formed in this region in a year. It is almost impossible to predict when this iceberg will break away from the glacier. However, specialists from the Institute of Polar and marine research named after Alfred Wegener (Germany) have achieved significant success in this matter. They learned about the factors that influence the movement of icebergs as they break off and can predict their path through the Southern Ocean.

“Icebergs, measuring no more than two kilometers in length or width, usually move away from the edge of the ice shelf within a few months. The wind blows them into the open sea, where they break up into small pieces and eventually melt in two to three years,” explains Thomas Rackow, a climate modeler at the Alfred Wegener Institute and one of the authors of the study.

For their research, Thomas Rakov and his colleagues created a computer model of the iceberg using its data and actual position. Potential routes derived from the computer were compared with data from existing large icebergs. The main goal of the experiment is to understand in which region of the Southern Ocean large icebergs will melt, thereby increasing the amount of fresh water.

When it comes to giant icebergs breaking off from the Larsen Glacier, the wind no longer plays a special role. Their movement is mainly due to their own weight, as well as the fact that the surface of the Southern Ocean is not perfectly flat, but has a slight slope to the north. Because of this, water levels at the southern edge of the Weddell Sea and along the entire Antarctic Peninsula could be half a meter higher than in the center. When large icebergs drift, they first slide down the sloping surface of the ocean, veering to the left and running parallel to the coast in the Antarctic Coastal Current. This is due to the Coriolis force, which is one of the inertial forces due to the rotation of the Earth.

But there are exceptions. Large table-shaped (flat) icebergs can deviate from the Coriolis force and linger near the coast for the first three or four years. But sooner or later they fall into a trap with drifting ice and sail away from the shore. Once the icebergs are in the open sea, they enter one of four “highways” that transport the floating glacier north. One of these routes follows the eastern coast of the Antarctic Peninsula. The second path is located on the prime meridian, on the eastern edge of the Weddell Sea, the third - on the Kerguelen Plateau in eastern Antarctica. The last remaining path leads the iceberg north from the Ross Sea.

Once icebergs begin their journey north, they will travel thousands of kilometers before melting. The largest of them even reach the shores of South America and New Zealand. How long a future Larsen Glacier iceberg will drift depends on whether it remains intact after calving. There is a possibility that it breaks up into smaller pieces. In addition, the iceberg can run aground. Thomas Rakov believes the iceberg has a chance of drifting for about a year across the Weddell Sea, along the coast of the Antarctic Peninsula. In this case, it will follow a northeasterly course to South Georgia and the South Sandwich Islands. Given its massive weight, the iceberg will stay afloat for eight to ten years. This is the maximum lifespan of wandering icebergs at the moment.