The thickness of this ice typically ranges from 0.3 m (0.98 ft) to 2 m (6.6 ft).
![density of sea water density of sea water](https://images.squarespace-cdn.com/content/v1/54a9bf74e4b0891d14c7561e/2ccaa605-43ec-474d-9b0a-2ea07b7e67f0/Fitnescity+DEXA+Scan.jpg)
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). Under compression, it will either raft (at the grey ice stage) or ridge (at the grey-white ice stage).įirst-year sea ice Distinction between 1st year sea ice (FY), 2nd year (SY), multiyear (MY) and old iceįirst-year sea ice is ice that is thicker than young ice but has no more than one year growth. Young ice is not as flexible as nilas, but tends to break under wave action. 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. 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. It bends without breaking around waves and swells. Nilas designates a sea ice crust up to 10 centimetres (3.9 in) in thickness. 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. Other terms, such as grease ice and pancake ice, are used for ice crystal accumulations under the action of wind and waves. 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). New ice is a general term used for recently frozen sea water that does not yet make up solid ice. New ice, nilas and young ice Nilas in Baffin Bay These stages are: new ice, nilas, young ice, first-year and old. Classification based on age Īnother classification used by scientists to describe sea ice is based on age, that is, on its development stages. The overall sea ice cover is termed the ice canopy from the perspective of submarine navigation. The term pack ice is used either as a synonym to drift ice, or to designate drift ice zone in which the floes are densely packed. Drift ice consists of floes, individual pieces of sea ice 20 metres (66 ft) or more across. The drift ice zone may be further divided into a shear zone, a marginal ice zone and a central pack. The physical boundary between fast ice and drift ice is the fast ice boundary. 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. If attached, it is called landfast ice, or more often, fast ice (from fastened). 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). For for the pseudoscientific use of the term, see Flood geology § Vapor/water canopy. Sea ice is classified according to whether or not it is able to drift and according to its age.įast ice versus drift (or pack) ice Due to the combined action of winds, currents, water temperature and air temperature fluctuations, sea ice expanses typically undergo a significant amount of deformation. General features and dynamics Hypothetical sea ice dynamics scenario showing some of the most common sea ice features (the bear provides an approximate scale) Depending on location, sea ice expanses may also incorporate icebergs. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Due to the action of winds, currents and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean.
![density of sea water density of sea water](https://cdn.wccftech.com/wp-content/uploads/2022/01/Cyberpunk-2077-Density.jpg)
Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). For other uses, see Polar ice packs (disambiguation).īroken pieces of Arctic sea ice with a snow cover