Sea ice – Wikipedia

Слово «айсберг» имеет скандинавские корни и означает «ледяная гора». Оно характеризует крупные глыбы льда, отколовшиеся от островных или континентальных ледников и дрейфующие в океанических, морских водах. Фото верхушки зеркальных гигантов, величаво возвышающихся над лазурной водой, демонстрируют лишь малую толику общего великолепия. Целостный образ складывается благодаря уникальным снимкам скрытого на 90% под водой мощного основания ледяных исполинов. Айсбергов одинаковых линий и форм не бывает. Идеальная с эстетической точки зрения задумка природы нашла воплощение во множестве неповторимых объектов.

Поскольку плотность льда составляет 920 кг/м³, а плотность морской воды — около 1025 кг/м³, около 90 % объёма айсберга находится под водой

Поскольку плотность льда составляет 920 кг/м³, а плотность морской воды — около 1025 кг/м³, около 90 % объёма айсберга находится под водой

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20 фото о настоящих размерах айсбергов

Источник:

Что такое айсберг

Слово «айсберг» имеет скандинавские корни и означает «ледяная гора». Оно характеризует крупные глыбы льда, отколовшиеся от островных или континентальных ледников и дрейфующие в океанических, морских водах.

Плавучие льды видны над поверхностью всего лишь на 10% от общего объема, остальная часть (90%) скрыта в глубине океанических вод. Такая пропорция физически обоснована соотношением плотности морской воды и пресного льда.

Айсберги. Какие бывают, фото под и над водой, интересные факты

В Северном полушарии редкие гигантские и небольшие ледяные островки, возвышающиеся не более чем на 5–6 м над океаном, в большинстве своем образуются в районе ледников Гренландии.

Оторвавшись от основы, они медленно дрейфуют на юг в сторону Северной Атлантики.

Айсберги Южного полушария начинают свой путь из Антарктиды.

Учеными подсчитан срок существования вновь образующихся айсбергов.

Свой путь от рождения до таяния в Антарктиде они проходят примерно за 2 года, а в Арктике — за 10 лет.

Любопытные факты:

Факт Информация
Количество ежегодно образуется до 40 тыс. новых айсбергов
Расположение большинство (93%) всех дрейфующих льдин курсирует вокруг Антарктики
Среднестатистические параметры вес плавучего льда средних размеров составляет от 100 тыс. т до 250 тыс. т, внутренняя температура — -15–20°
Скорость движения за сутки не более 24 км (15 миль)

добавить свое слово

Льдина

Отдельный кусок льда, дрейфующий на поверхности воды. Льдины бывают совершенно разных размеров. В Мировом океане, как правило, в приполярных областях существуют льдины огромных размеров 6 букв

Слово из 6 букв на букву Л, вторая буква Ь, третья буква Д, четвертая буква И, последняя буква А

General features and dynamics[edit]

Hypothetical sea ice dynamics scenario showing some of the most common sea ice features.

Sea ice does not simply grow and melt. During its lifespan, it is very dynamic. Due to the combined action of winds, currents, water temperature, and air temperature fluctuations, sea ice expanses typically undergo a significant amount of deformation. Sea ice is classified according to whether or not it is able to drift, and according to its age.

Fast ice versus drift (or pack) ice[edit]

Sea ice can be classified according to whether or not it is attached (or frozen) to the shoreline (or between shoals or to grounded icebergs). If attached, it is called landfast ice, or more often, fast ice (from fastened). Alternatively, and unlike fast ice, drift ice occurs further offshore in very wide areas, and encompasses ice that is free to move with currents and winds. The physical boundary between fast ice and drift ice is the fast ice boundary. The drift ice zone may be further divided into a shear zone, a marginal ice zone and a central pack.[4] Drift ice consists of floes, individual pieces of sea ice 20 metres (66 ft) or more across. There are names for various floe sizes: small – 20 to 100 m (66 to 328 ft); medium – 100 to 500 m (330 to 1,640 ft); big – 500 to 2,000 m (1,600 to 6,600 ft); vast – 2 to 10 kilometres (1.2 to 6.2 mi); and giant – more than 10 km (6.2 mi).[5][6] The term pack ice is used either as a synonym to drift ice,[5] or to designate drift ice zone in which the floes are densely packed.[5][6][7] The overall sea ice cover is termed the ice canopy from the perspective of submarine navigation.[6][7]

Classification based on age[edit]

Another classification used by scientists to describe sea ice is based on age, that is, on its development stages. These stages are: new ice, nilas, young ice, first-year and old.[5][6][7]

New ice, nilas and young ice[edit]

New ice is a general term used for recently frozen sea water that does not yet make up solid ice. It may consist of frazil ice (plates or spicules of ice suspended in water), slush (water saturated snow), or shuga (spongy white ice lumps a few centimeters across). Other terms, such as grease ice and pancake ice, are used for ice crystal accumulations under the action of wind and waves.[citation needed] When sea ice begins to form on a beach with a light swell, ice eggs up to the size of a football can be created.[8]

Nilas designates a sea ice crust up to 10 centimetres (3.9 in) in thickness. It bends without breaking around waves and swells. Nilas can be further subdivided into dark nilas – up to 5 cm (2.0 in) in thickness and very dark, and light nilas – over 5 cm (2.0 in) in thickness and lighter in color.

Young ice is a transition stage between nilas and first-year ice, and ranges in thickness from 10 cm (3.9 in) to 30 cm (12 in), Young ice can be further subdivided into grey ice – 10 cm (3.9 in) to 15 cm (5.9 in) in thickness, and grey-white ice – 15 cm (5.9 in) to 30 cm (12 in) in thickness. Young ice is not as flexible as nilas, but tends to break under wave action. Under compression, it will either raft (at the grey ice stage) or ridge (at the grey-white ice stage).

First-year sea ice[edit]

Distinction between 1st year sea ice (FY), 2nd year (SY), multiyear (MY) and old ice.

First-year sea ice is ice that is thicker than young ice but has no more than one year growth. In other words, it is ice that grows in the fall and winter (after it has gone through the new ice – nilas – young ice stages and grows further) but does not survive the spring and summer months (it melts away). The thickness of this ice typically ranges from 0.3 m (0.98 ft) to 2 m (6.6 ft).[5][6][7] First-year ice may be further divided into thin (30 cm (0.98 ft) to 70 cm (2.3 ft)), medium (70 cm (2.3 ft) to 120 cm (3.9 ft)) and thick (>120 cm (3.9 ft)).[6][7]

Old sea ice[edit]

Old sea ice is sea ice that has survived at least one melting season (i.e. one summer). For this reason, this ice is generally thicker than first-year sea ice. Old ice is commonly divided into two types: second-year ice, which has survived one melting season, and multiyear ice, which has survived more than one. (In some sources,[5] old ice is more than 2-years old.) Multi-year ice is much more common in the Arctic than it is in the Antarctic.[5][9] The reason for this is that sea ice in the south drifts into warmer waters where it melts. In the Arctic, much of the sea ice is land-locked.

Driving forces[edit]

While fast ice is relatively stable (because it is attached to the shoreline or the seabed), drift (or pack) ice undergoes relatively complex deformation processes that ultimately give rise to sea ice’s typically wide variety of landscapes. Wind is thought to be the main driving force along with ocean currents.[1][5] The Coriolis force and sea ice surface tilt have also been invoked.[5] These driving forces induce a state of stress within the drift ice zone. An ice floe converging toward another and pushing against it will generate a state of compression at the boundary between both. The ice cover may also undergo a state of tension, resulting in divergence and fissure opening. If two floes drift sideways past each other while remaining in contact, this will create a state of shear.

Deformation[edit]

Sea ice deformation results from the interaction between ice floes, as they are driven against each other. The end result may be of three types of features:[6][7] 1) Rafted ice, when one piece is overriding another; 2) Pressure ridges, a line of broken ice forced downward (to make up the keel) and upward (to make the sail); and 3) Hummock, an hillock of broken ice that forms an uneven surface. A shear ridge is a pressure ridge that formed under shear – it tends to be more linear than a ridge induced only by compression.[6][7] A new ridge is a recent feature – it is sharp-crested, with its side sloping at an angle exceeding 40 degrees. In contrast, a weathered ridge is one with a rounded crest and with sides sloping at less than 40 degrees.[6][7] Stamukhi are yet another type of pile-up but these are grounded and are therefore relatively stationary. They result from the interaction between fast ice and the drifting pack ice.

Level ice is sea ice that has not been affected by deformation, and is therefore relatively flat.[6][7]

Leads and polynyas[edit]

Leads and polynyas are areas of open water that occur within sea ice expanses even though air temperatures are below freezing, and provide a direct interaction between the ocean and the atmosphere, which is important for the wildlife. Leads are narrow and linear – they vary in width from meter to km scale. During the winter, the water in leads quickly freezes up. They are also used for navigation purposes – even when refrozen, the ice in leads is thinner, allowing icebreakers access to an easier sail path, and submarines to surface more easily. Polynyas are more uniform in size than leads and are also larger – two types are recognized: 1) Sensible-heat polynyas, caused by the upwelling of warmer water and 2) Latent-heat polynyas, resulting from persistent winds from the coastline.[5]

  • Aerial view showing an expanse of drift ice offshore Labrador (Eastern Canada) displaying floes of various sizes loosely packed, with open water in several networks of leads. (Scale not available.)

  • Aerial view showing an expanse of drift ice in southeastern Greenland, comprising loosely packed floes of various sizes, with a lead developing in the centre.(Scale not available.)

  • Aerial view showing an expanse of drift ice consisting mostly of water. (Scale not available.)

  • Close-up view inside a drift ice zone: several small rounded floes are separated from each other by slush or grease ice. (Bird at lower right for scale.)

  • Example of hummocky ice: an accumulation of ice blocks, here about 20 to 30 cm (7.9 to 11.8 in) in thickness (with a thin snow cover).

  • Field example of a pressure ridge. Only the sail (the part of the ridge above the ice surface) is shown in this photograph – the keel is more difficult to document.

  • Aerial view of the Chukchi Sea between Chukotka and Alaska, displaying a pattern of leads. Much of the open water inside those leads is already covered by new ice (indicated by a slightly lighter blue color)(scale not available).

Классификация по месторасположению

Выделяют следующие виды:

  1. Антарктические;
  2. Восточно-Гренландские;
  3. Дрейфующие ледяные острова;
  4. Евразийские айсберги;
  5. Западно-Гренландские.

Видео про самые большие айсберги

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