Canada
Canada is a country in the northern part of North America. Its ten provinces and three territories extend from the Atlantic to the Pacific and northward into the Arctic Ocean, covering 9.98 million square kilometres, making it the world's second-largest country by total area. Canada's southern border with the United States is the world's longest bi-national land border, its capital is Ottawa, its three largest metropolitan areas are Toronto and Vancouver. As a whole, Canada is sparsely populated, the majority of its land area being dominated by forest and tundra, its population is urbanized, with over 80 percent of its inhabitants concentrated in large and medium-sized cities, many near the southern border. Canada's climate varies across its vast area, ranging from arctic weather in the north, to hot summers in the southern regions, with four distinct seasons. Various indigenous peoples have inhabited what is now Canada for thousands of years prior to European colonization. Beginning in the 16th century and French expeditions explored, settled, along the Atlantic coast.
As a consequence of various armed conflicts, France ceded nearly all of its colonies in North America in 1763. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces; this began an accretion of provinces and territories and a process of increasing autonomy from the United Kingdom. This widening autonomy was highlighted by the Statute of Westminster of 1931 and culminated in the Canada Act of 1982, which severed the vestiges of legal dependence on the British parliament. Canada is a parliamentary democracy and a constitutional monarchy in the Westminster tradition, with Elizabeth II as its queen and a prime minister who serves as the chair of the federal cabinet and head of government; the country is a realm within the Commonwealth of Nations, a member of the Francophonie and bilingual at the federal level. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, education.
It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Canada's long and complex relationship with the United States has had a significant impact on its economy and culture. A developed country, Canada has the sixteenth-highest nominal per capita income globally as well as the twelfth-highest ranking in the Human Development Index, its advanced economy is the tenth-largest in the world, relying chiefly upon its abundant natural resources and well-developed international trade networks. Canada is part of several major international and intergovernmental institutions or groupings including the United Nations, the North Atlantic Treaty Organization, the G7, the Group of Ten, the G20, the North American Free Trade Agreement and the Asia-Pacific Economic Cooperation forum. While a variety of theories have been postulated for the etymological origins of Canada, the name is now accepted as coming from the St. Lawrence Iroquoian word kanata, meaning "village" or "settlement".
In 1535, indigenous inhabitants of the present-day Quebec City region used the word to direct French explorer Jacques Cartier to the village of Stadacona. Cartier used the word Canada to refer not only to that particular village but to the entire area subject to Donnacona. From the 16th to the early 18th century "Canada" referred to the part of New France that lay along the Saint Lawrence River. In 1791, the area became two British colonies called Upper Canada and Lower Canada collectively named the Canadas. Upon Confederation in 1867, Canada was adopted as the legal name for the new country at the London Conference, the word Dominion was conferred as the country's title. By the 1950s, the term Dominion of Canada was no longer used by the United Kingdom, which considered Canada a "Realm of the Commonwealth"; the government of Louis St. Laurent ended the practice of using'Dominion' in the Statutes of Canada in 1951. In 1982, the passage of the Canada Act, bringing the Constitution of Canada under Canadian control, referred only to Canada, that year the name of the national holiday was changed from Dominion Day to Canada Day.
The term Dominion was used to distinguish the federal government from the provinces, though after the Second World War the term federal had replaced dominion. Indigenous peoples in present-day Canada include the First Nations, Métis, the last being a mixed-blood people who originated in the mid-17th century when First Nations and Inuit people married European settlers; the term "Aboriginal" as a collective noun is a specific term of art used in some legal documents, including the Constitution Act 1982. The first inhabitants of North America are hypothesized to have migrated from Siberia by way of the Bering land bridge and arrived at least 14,000 years ago; the Paleo-Indian archeological sites at Old Crow Flats and Bluefish Caves are two of the oldest sites of human habitation in Canada. The characteristics of Canadian indigenous societies included permanent settlements, complex societal hierarchies, trading networks; some of these cultures had collapsed by the time European explorers arrived in the late 15th and early 16th centuries and have only been discovered through archeological investigations.
The indigenous population at the time of the first European settlements is estimated to have been between 200,000
Ernest Shackleton
Sir Ernest Henry Shackleton was a British polar explorer who led three British expeditions to the Antarctic. He was one of the principal figures of the period known as the Heroic Age of Antarctic Exploration. Born in Kilkea, County Kildare, Ireland and his Anglo-Irish family moved to Sydenham in suburban south London when he was ten, his first experience of the polar regions was as third officer on Captain Robert Falcon Scott's Discovery Expedition 1901–1904, from which he was sent home early on health grounds, after he and his companions Scott and Edward Adrian Wilson set a new southern record by marching to latitude 82°S. During the second expedition 1907–1909 he and three companions established a new record Farthest South latitude at 88°S, only 97 geographical miles from the South Pole, the largest advance to the pole in exploration history. Members of his team climbed Mount Erebus, the most active Antarctic volcano. For these achievements, Shackleton was knighted by King Edward VII on his return home.
After the race to the South Pole ended in December 1911 with Roald Amundsen's conquest, Shackleton turned his attention to the crossing of Antarctica from sea to sea, via the pole. To this end, he made preparations for what became the Imperial Trans-Antarctic Expedition, 1914–17. Disaster struck this expedition when its ship, became trapped in pack ice and was crushed before the shore parties could be landed; the crew escaped by camping on the sea ice until it disintegrated by launching the lifeboats to reach Elephant Island and the inhabited island of South Georgia, a stormy ocean voyage of 720 nautical miles and Shackleton's most famous exploit. In 1921, he returned to the Antarctic with the Shackleton–Rowett Expedition, but died of a heart attack while his ship was moored in South Georgia. At his wife's request, he was buried there. Away from his expeditions, Shackleton's life was restless and unfulfilled. In his search for rapid pathways to wealth and security, he launched business ventures which failed to prosper, he died in debt.
Upon his death, he was lauded in the press but was thereafter forgotten, while the heroic reputation of his rival Scott was sustained for many decades. In the 20th century, Shackleton was "rediscovered", became a role model for leadership as one who, in extreme circumstances, kept his team together in a survival story described by cultural historian Stephanie Barczewski as "incredible". In his 1956 address to the British Association, Sir Raymond Priestley, one of his contemporaries, said "Scott for scientific method, Amundsen for speed and efficiency but when disaster strikes and all hope is gone, get down on your knees and pray for Shackleton", paraphrasing what Apsley Cherry-Garrard had written in a preface to The Worst Journey in the World. In 2002, Shackleton was voted eleventh in a BBC poll of the 100 Greatest Britons. Shackleton was born on 15 February 1874 in Kilkea, County Kildare, United Kingdom of Great Britain and Ireland, his father, Henry Shackleton, tried to enter the army, but his poor health prevented him from doing so.
He became a farmer instead. The Shackleton family are of English origin from Yorkshire. Abraham Shackleton, an English Quaker, moved to Ireland in 1726 and started a school at Ballitore, County Kildare. Shackleton's mother, Henrietta Letitia Sophia Gavan, was descended from the Fitzmaurices, an Anglo-Irish family which had arrived in Ireland during the Anglo-Norman Invasion. Ernest was the first of two sons. In 1880, when Ernest was six, Henry Shackleton gave up his life as a landowner to study medicine at Trinity College, moving his family to the city. Four years the family moved again, from Ireland to Sydenham in suburban London; this was in search of better professional prospects for the newly qualified doctor, but another factor may have been unease about their Anglo-Irish ancestry, following the assassination by Irish nationalists of Lord Frederick Cavendish, the British Secretary for Ireland, in 1882. From early childhood, Shackleton was a voracious reader, a pursuit which sparked a passion for adventure.
He was schooled by a governess until the age of eleven, when he began at Fir Lodge Preparatory School in West Hill, Dulwich, in southeast London. At the age of thirteen, he entered Dulwich College; the young Shackleton did not distinguish himself as a scholar, was said to be "bored" by his studies. He was quoted as saying: "I never learned much geography at school... Literature, consisted in the dissection, the parsing, the analysing of certain passages from our great poets and prose-writers... teachers should be careful not to spoil taste for poetry for all time by making it a task and an imposition." In his final term at the school he was still able to achieve fifth place in his class of thirty-one. Shackleton's restlessness at school was such that he was allowed to go to sea; the options available were a Royal Naval cadetship at HMS Britannia, which Dr Shackleton could not afford. The third option was chosen, his father was able to secure him a berth with the North Western Shipping Company, aboard the square-rigged sailing ship Hoghton Tower.
During the following four years at sea, Shackleton learned his trade, visiting the far corners of the earth and forming acquaintances with a variety of people from m
Sublimation (phase transition)
Sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase. Sublimation is an endothermic process that occurs at temperatures and pressures below a substance's triple point in its phase diagram, which corresponds to the lowest pressure at which the substance can exist as a liquid; the reverse process of sublimation is deposition or desublimation, in which a substance passes directly from a gas to a solid phase. Sublimation has been used as a generic term to describe a solid-to-gas transition followed by a gas-to-solid transition. While a transition from liquid to gas is described as evaporation if it occurs below the boiling point of the liquid, as boiling if it occurs at the boiling point, there is no such distinction within the solid-to-gas transition, always described as sublimation. At normal pressures, most chemical compounds and elements possess three different states at different temperatures. In these cases, the transition from the solid to the gaseous state requires an intermediate liquid state.
The pressure referred to is the partial pressure of the substance, not the total pressure of the entire system. So, all solids that possess an appreciable vapour pressure at a certain temperature can sublime in air. For some substances, such as carbon and arsenic, sublimation is much easier than evaporation from the melt, because the pressure of their triple point is high, it is difficult to obtain them as liquids; the term sublimation refers to a physical change of state and is not used to describe the transformation of a solid to a gas in a chemical reaction. For example, the dissociation on heating of solid ammonium chloride into hydrogen chloride and ammonia is not sublimation but a chemical reaction; the combustion of candles, containing paraffin wax, to carbon dioxide and water vapor is not sublimation but a chemical reaction with oxygen. Sublimation is caused by the absorption of heat which provides enough energy for some molecules to overcome the attractive forces of their neighbors and escape into the vapor phase.
Since the process requires additional energy, it is an endothermic change. The enthalpy of sublimation can be calculated by adding the enthalpy of fusion and the enthalpy of vaporization. Solid carbon dioxide sublimes everywhere along the line below the triple point (e.g. at the temperature of −78.5 °C at atmospheric pressure, whereas its melting into liquid CO2 can occur only along the line at pressures and temperatures above the triple point. Snow and ice sublime, although more at temperatures below the freezing/melting point temperature line at 0 °C for most pressures. In freeze-drying, the material to be dehydrated is frozen and its water is allowed to sublime under reduced pressure or vacuum; the loss of snow from a snowfield during a cold spell is caused by sunshine acting directly on the upper layers of the snow. Ablation is a process that includes erosive wear of glacier ice. Naphthalene, an organic compound found in pesticides such as mothballs, sublimes because it is made of non-polar molecules that are held together only by van der Waals intermolecular forces.
Naphthalene is a solid that sublimes at standard atmospheric temperature with the sublimation point at around 80 °C or 176 °F. At low temperature, its vapour pressure is high enough, 1 mmHg at 53 °C, to make the solid form of naphthalene evaporate into gas. On cool surfaces, the naphthalene vapours will solidify to form needle-like crystals. Iodine produces fumes on gentle heating, it is possible to obtain liquid iodine at atmospheric pressure by controlling the temperature at just above the melting point of iodine. In forensic science, iodine vapor can reveal latent fingerprints on paper. Arsenic can sublime at high temperatures. Cadmium and zinc are not suitable materials for use in vacuum because they sublimate much more than other common materials. Sublimation is a technique used by chemists to purify compounds. A solid is placed in a sublimation apparatus and heated under vacuum. Under this reduced pressure, the solid volatilizes and condenses as a purified compound on a cooled surface, leaving a non-volatile residue of impurities behind.
Once heating ceases and the vacuum is removed, the purified compound may be collected from the cooling surface. For higher purification efficiencies, a temperature gradient is applied, which allows for the separation of different fractions. Typical setups use an evacuated glass tube, heated in a controlled manner; the material flow is from the hot end, where the initial material is placed, to the cold end, connected to a pump stand. By controlling temperatures along the length of the tube, the operator can control the zones of re-condensation, with volatile compounds being pumped out of the system moderately volatile compounds re-condensing along the tube according to their different volatilities, non-volatile compounds remaining in the hot end. Vacuum sublimation of this type is the method of choice for purification of organic compounds for use in the organic electronics industry, where high purities are needed to satisfy the standards for consumer electronics and other applications. In ancient alchemy, a protoscience that contributed to the development of modern chemistry and medicine, alchemists developed a structure of basic laboratory techniques, theory and experimental methods.
Sublimation was used to refer to the process in which a
Snowboard
Snowboards are boards where both feet are secured to the same board, which are wider than skis, with the ability to glide on snow. Snowboards widths are 15 to 30 centimeters. Snowboards are differentiated from monoskis by the stance of the user. In monoskiing, the user stands with feet inline with direction of travel, whereas in snowboarding, users stand with feet transverse to the longitude of the board. Users of such equipment may be referred to as snowboarders. Commercial snowboards require extra equipment such as bindings and special boots which help secure both feet of a snowboarder, who rides in an upright position; these types of boards are used by people at ski hills or resorts for leisure and competitive purposes in the activity called snowboarding. In 1939, Vern Wicklund, at the age of 13, fashioned a shred deck in Minnesota; this modified sled was dubbed a "bunker" by his friends. He, along with relatives Harvey and Gunnar Burgeson, patented the first snowboard twenty two years later.
However, a man by the name of Sherman Poppen, from Muskegon, MI, came up with what most consider the first "snowboard" in 1965 and was called the Snurfer who sold his first 4 "snurfers" to Randall Baldwin Lee of Muskegon, MI who worked at Outdoorsman Sports Center 605 Ottawa Street in Muskegon, MI. Randy believes that Sherman took an old water ski and made it into the snurfer for his children who were bored in the winter, he added bindings to keep their boots secure. Commercially available Snurfers in the late 1960s and early 1970s had no bindings; the snowboarder held onto a looped nylon lanyard attached to the front of the Snurfer, stood upon several rows of square U-shaped staples that were driven into the board but protruded about 1 cm above the board's surface to provide traction when packed with snow. Snurfer models replaced the staples with ridged rubber grips running longitudinally along the length of the board or, subsequently, as subrectangular pads upon which the snowboarder would stand.
It is accepted that Jake Burton Carpenter and/or Tom Sims invented modern snowboarding by introducing bindings and steel edges to snowboards. In 1981, a couple of Winterstick team riders went to France at the invitation of Alain Gaimard, marketing director at Les Arcs. After seeing an early film of this event, French skiers/surfers Augustin Coppey, Olivier Lehaneur, Olivier Roland and Antoine Yarmola made their first successful attempts during the winter of 1983 in France, using primitive, home-made clones of the Winterstick. Starting with pure powder, skateboard-shaped wooden-boards equipped with aluminium fins, foot-straps and leashes, their technology evolved within a few years to pressed wood/fiber composite boards fitted with polyethylene soles, steel edges and modified ski boot shells; these were more suitable for the mixed conditions encountered while snowboarding off-piste, but having to get back to ski lifts on packed snow. In 1985, James Bond popularized snowboarding in the movie A View to a Kill.
In the scene, he escapes Soviet agents. The snowboard he used was a Sims snowboard ridden by founder Tom Sims; the makeshift snowboard was made from the debris of a snowmobile. At the same time the Snurfer was turning into a snowboard on the other side of the iron curtain. In 1980, Aleksey Ostatnigrosh and Alexei Melnikov - two members of the only Snurfer club in the Soviet Union started changing the Snurfer design to allow jumping and to improve control on hard packed snow. Being unaware of the developments in the Snurfer/snowboard world, they attached a bungee cord to the Snurfer tail which the rider could grab before jumping. In 1982, they attached a foot binding to the Snurfer; the binding was only for the back foot, had a release capability. In 1985, after several iterations of the Snurfer binding system, Aleksey Ostatnigrosh made the first Russian snowboard; the board had no metal edges. The bindings were attached by a central bolt and could rotate while on the move or be fixed at any angle.
In 1988, OstatniGROsh and MELnikov started the first Russian snowboard manufacturing company, GROMEL. By 1986, although still much a minority sport, commercial snowboards started appearing in leading French ski resorts. In 2008, selling snowboarding equipment was a $487 million industry. In 2008, average equipment ran about $540 including board and bindings; the bottom or'base' of the snowboard is made of UHMW and is surrounded by a thin strip of steel, known as the'edge'. Artwork was printed on PBT using a sublimation process in the 1990s, but poor color retention and fade after moderate use moved high-end producers to longer-lasting materials. Snowboards come in several different styles, depending on the type of riding intended: Freestyle: Generally shorter with moderate to soft flex. Freestyle snowboards have a mirror shovel at each end of the board. Freestyle snowboards have low-backed bindings. Incorporates a deep sidecut for quick/tight turning. Used in the pipe and in the park on various jumps and terrain features including boxes and urban features.
Park/Jib: Flexible and short to medium length, twin-tip shape with a twin flex and an outward stance to allow easy switch riding, easy spinning, a wider stance, with the edges filed dull is used for skateboard-park like snowboard parks. Freeride: Longer than freestyle and park boards
Snow cornice
A snow cornice or cornice is an overhanging edge of snow on a ridge or the crest of a mountain and along the sides of gullies. They form by wind blowing snow over sharp terrain breaks where it attaches and builds out horizontally; this build-up is most common on the leeward sides of mountains. Cornices are dangerous and travelling above or below them should be avoided; when a cornice collapses, it breaks in from the cornice to the top of the peak. The best practice in mountaineering is to stay far enough back from the edge so as not to be able to see the drop, as an approximate metric of exposure. In avalanche safety, cornices are a high avalanche danger as they break and trigger larger avalanches that permeate several snow layers. Cornices are vulnerable to collapse during periods of solar warming. List of climbing topics Sastrugi Media related to Snow cornices at Wikimedia Commons Cornice from the Avalanche Encyclopedia Climber found dead in Mount St. Helens crater after falling through cornice'A great tragedy:' Bodies of 5 missing hikers recovered near Lions Bay, B.
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Erosion
In earth science, erosion is the action of surface processes that removes soil, rock, or dissolved material from one location on the Earth's crust, transports it to another location. This natural process is caused by the dynamic activity of erosive agents, that is, ice, air, plants and humans. In accordance with these agents, erosion is sometimes divided into water erosion, glacial erosion, snow erosion, wind erosion, zoogenic erosion, anthropogenic erosion; the particulate breakdown of rock or soil into clastic sediment is referred to as physical or mechanical erosion. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Natural rates of erosion are controlled by the action of geological weathering geomorphic drivers, such as rainfall; the rates at which such processes act control. Physical erosion proceeds fastest on steeply sloping surfaces, rates may be sensitive to some climatically-controlled properties including amounts of water supplied, wind speed, wave fetch, or atmospheric temperature.
Feedbacks are possible between rates of erosion and the amount of eroded material, carried by, for example, a river or glacier. Processes of erosion that produce sediment or solutes from a place contrast with those of deposition, which control the arrival and emplacement of material at a new location. While erosion is a natural process, human activities have increased by 10-40 times the rate at which erosion is occurring globally. At well-known agriculture sites such as the Appalachian Mountains, intensive farming practices have caused erosion up to 100x the speed of the natural rate of erosion in the region. Excessive erosion causes both "on-site" and "off-site" problems. On-site impacts include decreases in agricultural productivity and ecological collapse, both because of loss of the nutrient-rich upper soil layers. In some cases, the eventual end result is desertification. Off-site effects include sedimentation of waterways and eutrophication of water bodies, as well as sediment-related damage to roads and houses.
Water and wind erosion are the two primary causes of land degradation. Intensive agriculture, roads, anthropogenic climate change and urban sprawl are amongst the most significant human activities in regard to their effect on stimulating erosion. However, there are many prevention and remediation practices that can curtail or limit erosion of vulnerable soils. Rainfall, the surface runoff which may result from rainfall, produces four main types of soil erosion: splash erosion, sheet erosion, rill erosion, gully erosion. Splash erosion is seen as the first and least severe stage in the soil erosion process, followed by sheet erosion rill erosion and gully erosion. In splash erosion, the impact of a falling raindrop creates a small crater in the soil, ejecting soil particles; the distance these soil particles travel can be as much as 0.6 m vertically and 1.5 m horizontally on level ground. If the soil is saturated, or if the rainfall rate is greater than the rate at which water can infiltrate into the soil, surface runoff occurs.
If the runoff has sufficient flow energy, it will transport loosened soil particles down the slope. Sheet erosion is the transport of loosened soil particles by overland flow. Rill erosion refers to the development of small, ephemeral concentrated flow paths which function as both sediment source and sediment delivery systems for erosion on hillslopes. Where water erosion rates on disturbed upland areas are greatest, rills are active. Flow depths in rills are of the order of a few centimetres or less and along-channel slopes may be quite steep; this means that rills exhibit hydraulic physics different from water flowing through the deeper, wider channels of streams and rivers. Gully erosion occurs when runoff water accumulates and flows in narrow channels during or after heavy rains or melting snow, removing soil to a considerable depth. Valley or stream erosion occurs with continued water flow along a linear feature; the erosion is both downward, deepening the valley, headward, extending the valley into the hillside, creating head cuts and steep banks.
In the earliest stage of stream erosion, the erosive activity is dominantly vertical, the valleys have a typical V cross-section and the stream gradient is steep. When some base level is reached, the erosive activity switches to lateral erosion, which widens the valley floor and creates a narrow floodplain; the stream gradient becomes nearly flat, lateral deposition of sediments becomes important as the stream meanders across the valley floor. In all stages of stream erosion, by far the most erosion occurs during times of flood when more and faster-moving water is available to carry a larger sediment load. In such processes, it is not the water alone
Sea ice
Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface. Sea ice covers 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 and temperature fluctuations, sea ice is 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 incorporate icebergs. Sea ice does not grow and melt. During its lifespan, it is dynamic. Due to the combined action of winds, water temperature, air temperature fluctuations, sea ice expanses undergo a significant amount of deformation.
Sea ice is classified according to whether or not it is able to drift, according to its age. Sea ice can be classified according to whether or not it is attached to the shoreline. If attached, it is called landfast ice, or more fast ice. Alternatively, unlike fast ice, drift ice occurs further offshore in wide areas, encompasses ice, 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 marginal ice zone and a central pack. Drift ice consists of floes, individual pieces of sea ice 20 metres or more across. There are names for various floe sizes: small – 20 to 100 m; 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. The overall sea ice cover is termed the ice canopy from the perspective of submarine navigation. Another classification used by scientists to describe sea ice is based on age, that is, on its development stages.
These stages are: new ice, young ice, first-year and old. New ice is a general term used for frozen sea water that does not yet make up solid ice, it may consist of slush, or shuga. Other terms, such as grease ice and pancake ice, are used for ice crystal accumulations under the action of wind and waves. Nilas designates a sea ice crust up to 10 centimetres in thickness, it swells. Nilas can be further subdivided into dark nilas – up to 5 cm in thickness and dark, light nilas – over 5 cm in thickness and lighter in color. Young ice is a transition stage between nilas and first-year ice, ranges in thickness from 10 cm to 30 cm, Young ice can be further subdivided into grey ice – 10 cm to 15 cm in thickness, grey-white ice – 15 cm to 30 cm in thickness. Young ice is not as flexible as tends to break under wave action. In a compression regime, it will either ridge. First-year sea ice is ice, 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 but does not survive the spring and summer months.
The thickness of this ice ranges from 0.3 m to 2 m. First-year ice may be further divided into thin and thick. Old sea ice is sea ice. For this reason, this ice is thicker than first-year sea ice. Old ice is divided into two types: second-year ice, which has survived one melting season, multiyear ice, which has survived more than one. Multi-year ice is much more common in the Arctic; the reason for this is. In the Arctic, much of the sea ice is land-locked. While fast ice is stable, drift ice undergoes complex deformation processes that give rise to sea ice's wide variety of landscapes. Wind is thought to be the main driving force along with ocean currents; the Coriolis force and sea ice surface tilt have been invoked. 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 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. 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: 1) Rafted ice, when one piece is overriding another.
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