Isostasy or isostatic equilibrium is the state of gravitational equilibrium between Earth's crust and mantle such that the crust "floats" at an elevation that depends on its thickness and density. This concept is invoked to explain how different topographic heights can exist at Earth's surface. Although originally defined in terms of continental crust and mantle, it has subsequently been interpreted in terms of lithosphere and asthenosphere, particularly with respect to oceanic island volcanoes, such as the Hawaiian Islands.
Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface. Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. 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. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. 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. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Depending on location, sea ice expanses may also incorporate icebergs.
An icebreaker is a special-purpose ship or boat designed to move and navigate through ice-covered waters, and provide safe waterways for other boats and ships. Although the term usually refers to ice-breaking ships, it may also refer to smaller vessels, such as the icebreaking boats that were once used on the canals of the United Kingdom.
A ship model basin is a basin or tank used to carry out hydrodynamic tests with ship models, for the purpose of designing a new ship, or refining the design of a ship to improve the ship's performance at sea. It can also refer to the organization that owns and operates such a facility.
CCGS Terry Fox is a Canadian Coast Guard heavy icebreaker. She was originally built by Burrard-Yarrows Corporation in Canada in 1983 as part of an Arctic drilling system developed by BeauDril, the drilling subsidiary of Gulf Canada Resources. After the offshore oil exploration in the Beaufort Sea ended in the early 1990s, she was first leased and then sold to the Canadian Coast Guard.
MSV Fennica is a Finnish multipurpose icebreaker and offshore support vessel. Built in 1993 by Finnyards in Rauma, Finland and operated by Arctia Offshore, she was the first Finnish icebreaker designed to be used as an escort icebreaker in the Baltic Sea during the winter months and in offshore construction projects during the open water season. Fennica has an identical sister ship, Nordica, built in 1994.
An icemaker, ice generator, or ice machine may refer to either a consumer device for making ice, found inside a home freezer; a stand-alone appliance for making ice, or an industrial machine for making ice on a large scale. The term "ice machine" usually refers to the stand-alone appliance.
An ice road or ice bridge is a human-made structure that runs on a frozen water surface. Ice roads are typically part of a winter road, but they can also be simple stand-alone structures, connecting two shorelines. Ice roads may be planned, built and maintained so as to remain safe and effective, and a number of guidelines have been published with information in these regards. An ice road may be constructed year after year, for instance to service community needs during the winter. It could also be for a single year or two, so as to supply particular operations, such as a hydroelectric project or offshore drill sites.
Ice sheet dynamics describe the motion within large bodies of ice such as those currently on Greenland and Antarctica. Ice motion is dominated by the movement of glaciers, whose gravity-driven activity is controlled by two main variable factors: the temperature and the strength of their bases. A number of processes alter these two factors, resulting in cyclic surges of activity interspersed with longer periods of inactivity, on both hourly and centennial time scales. Ice-sheet dynamics are of interest in modelling future sea level rise.
Pumpable icetechnology (PIT) uses thin liquids, with the cooling capacity of ice. Pumpable ice is typically a slurry of ice crystals or particles ranging from 5 micrometers to 1 cm in diameter and transported in brine, seawater, food liquid, or gas bubbles of air, ozone, or carbon dioxide.
A double acting ship is a type of icebreaking ship designed to travel forwards in open water and thin ice, but turn around and proceed astern (backwards) in heavy ice conditions. In this way, the ship can operate independently in severe ice conditions without icebreaker assistance but retain better open water performance than traditional icebreaking vessels.
Kontio is a Finnish state-owned icebreaker. Built by Wärtsilä Helsinki shipyard in 1987 as a replacement for the aging Karhu-class icebreakers, she and her sister ship Otso were the first Finnish post-war icebreaker to be built without bow propellers.
With increased interest in sea ice and its effects on the global climate, efficient methods are required to monitor both its extent and exchange processes. Satellite-mounted, microwave radiometers, such SSMI, AMSR and AMSU, are an ideal tool for the task because they can see through cloud cover, and they have frequent, global coverage. A passive microwave instrument detects objects through emitted radiation since different substance have different emission spectra. To detect sea ice more efficiently, there is a need to model these emission processes. The interaction of sea ice with electromagnetic radiation in the microwave range is still not well understood. In general is collected information limited because of the large-scale variability due to the emissivity of sea ice.
The Resonance method of ice destruction means breaking sheet-ice which has formed over a body of water by causing the ice and water to oscillate up and down until the ice suffers sufficient mechanical fatigue to cause a fracture.
SA-15 is the project name for a series of icebreaking multipurpose cargo ships built in Finland for the Soviet Union in the 1980s. The ships, capable of independent operation in all prevailing arctic ice conditions, were the first merchant vessels designed for year-round operations in the Northern Sea Route. For this purpose they have hulls that resemble those of polar icebreakers and propulsion systems capable of withstanding ice loads.
Otso is a Finnish state-owned icebreaker. Built by Wärtsilä Helsinki shipyard in 1986 to replace the aging Karhu-class icebreakers, she was the first Finnish post-war icebreaker to be built without bow propellers. Otso has an identical sister ship, Kontio, which was delivered in 1987.
Finger rafting develops in an ice cover as a result of a compression regime established within the plane of the ice. As two expanses of sea ice converge toward another, one of them slides smoothly on top of the other along a given distance, resulting in a local increase in ice thickness. The term finger rafting refers to the systematic alternation of interlocking overthrusts and underthrusts involved in this process. Such a pattern derives its name from its resemblance to the interlocking of fingers.
Martian regolith simulant is a terrestrial material that is used to simulate the chemical and mechanical properties of Martian regolith for research, experiments and prototype testing of activities related to Martian regolith such as dust mitigation of transportation equipment, advanced life support systems and in-situ resource utilization.
Antarctic sea ice is the sea ice of the Southern Ocean. It extends from the far north in the winter and retreats to almost the coastline every summer. Sea ice is frozen seawater that is usually less than a few meters thick. This is the opposite of ice shelves, which are formed by glaciers; they float in the sea, and are up to a kilometre thick. There are two subdivisions of sea ice: fast ice, which are attached to land; and ice floes, which are not.
Mudyug is a Russian icebreaker and the lead ship of a series of three subarctic icebreakers built at Wärtsilä Helsinki shipyard in Finland in 1982–1983. The vessel's non-rebuilt sister ships are Magadan and Dikson.
