Ice
Ice is water frozen into a solid state. Depending on the presence of such as particles of soil or bubbles of air. In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far as away the Oort cloud objects, beyond the Solar System, it occurs as interstellar ice. It falls as snowflakes and hail or occurs as frost, icicles or ice spikes, Ice molecules can exhibit up to sixteen different phases that depend on temperature and pressure. When water is cooled rapidly, up to three different types of ice can form depending on the history of its pressure and temperature. When cooled slowly correlated proton tunneling occurs below 20 K giving rise to macroscopic quantum phenomena, virtually all the ice on Earths surface and in its atmosphere is of a hexagonal crystalline structure denoted as ice Ih with minute traces of cubic ice denoted as ice Ic. The most common phase transition to ice Ih occurs when water is cooled below 0°C at standard atmospheric pressure.
It may be deposited directly by water vapor, as happens in the formation of frost, the transition from ice to water is melting and from ice directly to water vapor is sublimation. Ice is used in a variety of ways, including cooling, winter sports, as a naturally occurring crystalline inorganic solid with an ordered structure, ice is considered a mineral. It possesses a regular crystalline structure based on the molecule of water, an unusual property of ice frozen at atmospheric pressure is that the solid is approximately 8. 3% less dense than liquid water. The density of ice is 0.9167 g/cm3 at 0 °C, liquid water is densest, essentially 1.00 g/cm³, at 4 °C and becomes less dense as the water molecules begin to form the hexagonal crystals of ice as the freezing point is reached. This is due to hydrogen bonding dominating the intermolecular forces, which results in a packing of molecules less compact in the solid, density of ice increases slightly with decreasing temperature and has a value of 0.9340 g/cm³ at −180 °C.
When water freezes, it increases in volume and it is a common cause of the flooding of houses when water pipes burst due to the pressure of expanding water when it freezes. The result of this process is that ice floats on liquid water, sufficiently thin ice sheets allow light to pass through while protecting the underside from short-term weather extremes such as wind chill. This creates an environment for bacterial and algal colonies. When ice melts, it absorbs as much energy as it would take to heat an equivalent mass of water by 80 °C, during the melting process, the temperature remains constant at 0 °C. While melting, any energy added breaks the bonds between ice molecules. Energy becomes available to increase the thermal energy only after enough hydrogen bonds are broken that the ice can be considered liquid water, the amount of energy consumed in breaking hydrogen bonds in the transition from ice to water is known as the heat of fusion
Drift ice
Drift ice is any sea ice other than fast ice, the latter being attached to the shoreline or other fixed objects. Drift ice is carried along by winds and sea currents, hence its name, when drift ice is driven together into a large single mass, it is called pack ice. Wind and currents can pile up that ice to form ridges up to several metres in height and these represent a challenge for icebreakers and offshore structures operating in cold oceans and seas. Drift ice consists of floes, individual pieces of sea ice 20 metres or more across. Seasonal ice drift in the Sea of Okhotsk by the northern coast of Hokkaidō, Japan has become a tourist attraction of this area with harsh climate, the Sea of Okhotsk is the southernmost area in the Northern hemisphere where drift ice may be observed. Drift ice affects, Security of navigation Climatic impact Geological impact Biosphere influence The two major ice packs are the Arctic ice pack and the Antarctic ice pack, polar packs significantly change their size during seasonal changes of the year.
Because of vast amounts of water added to or removed from the oceans and atmosphere, the behavior of polar ice packs has a significant impact on global changes in climate
Antarctic Sound
The Antarctic Sound is a body of water about 30 nautical miles long and from 7 to 12 nautical miles wide, separating the Joinville Island group from the northeast end of the Antarctic Peninsula. Since 2005 cruise ships have been visiting the area, the northern limit of the sound, where it joins the Bransfield Strait, is the line connecting Cape Dubouzet on Trinity Peninsula with Turnbull Point on DUrville Island. The southern limit is the line connecting Cape Scrymgeour on Andersson Island with Cape Purvis on Dundee Island, the sound is 30 nautical miles long and from 7 to 12 nautical miles wide. The Tabarin Peninsula forms the southwestern coast of the Antarctic Sound and contains several bays, the Antarctic Sound was first navigated by the vessel Antarctic belonging to the Swedish Antarctic Expedition of 1902, captained by Otto Nordenskjöld. Hope Bay was at one time the site of a British base, Hope Bay has been recognised as an Important Bird Area. Birds that breed here include the gentoo penguin, brown skua, Antarctic tern, Wilsons storm petrel, kelp gull and it houses one of the largest breeding colonies of Adélie penguin in Antarctica.
At Trepassey Bay, gentoo and Adélie penguins breed, as well as Cape petrels, snow petrels, weddell seals often haul out on the beach and leopard seals hunt offshore. This article incorporates public domain material from the United States Geological Survey document Antarctic Sound
Iceberg B-15
Iceberg B-15 was the worlds largest recorded iceberg. It measured around 295 kilometres long and 37 kilometres wide, with an area of 11,000 square kilometres —larger than the whole island of Jamaica. Calved from the Ross Ice Shelf of Antarctica in March 2000, Iceberg B-15 broke up into smaller icebergs, in 2003, B-15A drifted away from Ross Island into the Ross Sea and headed north, eventually breaking up into several smaller icebergs in October 2005. In the last weeks of March 2000, Iceberg B-15 calved from the Ross Ice Shelf near Roosevelt Island, the calving occurred along pre-existing cracks in the ice shelf. The iceberg measured around 295 kilometres long and 37 kilometres wide, scientists believe that the enormous piece of ice broke away as part of a long-term natural cycle, which occurs every fifty to one hundred years. In 2000,2002, and 2003, Iceberg B-15 broke up several pieces. In November 2003, after the separation from B-15J, B-15A drifted away from Ross Island on the waters of the Ross Sea.
In December 2003, a small knife-shaped iceberg, B-15K, detached itself from the body of B-15A. A few kilometres from the ice tongue, the iceberg became stranded on a shallow seamount before resuming its northward course, on 10 April 2005, B-15A collided with the ice tongue, breaking off the tip of the ice tongue, the iceberg seemed unaffected by the collision. Iceberg B-15A continued to drift along the coast leaving McMurdo Sound, on 27–28 October 2005, the iceberg ran aground off Cape Adare in Victoria Land and broke into several smaller pieces, the largest of which was still named B-15A. Three additional pieces were named B-15P, B-15M, and B-15N, Iceberg B-15A moved farther up north and broke up into more pieces. These were spotted by air force fisheries patrol on 3 November 2006, on 21 November 2006 several large pieces were seen just 60 km off the coast of Timaru, New Zealand—the largest measured about 18 kilometres, rising 37 metres from the surface of the ocean. On 29 January 2001, researchers from the University of Chicago and it was the first time an iceberg had been monitored in this way.
The data gathered led to an understanding of how giant icebergs make their way through the waters of Antarctica. Iceberg B-15A collided with the Drygalski Ice Tongue on 10 April 2005, antarctic maps needed to be redrawn. B-15A prevented ocean currents and winds from assisting in the 2004–2005 summer break-up of the sea ice in McMurdo Sound, and was an obstacle to the annual resupply ships to three research stations. The floe was expected to cause a decline in the population of Adélie penguins. Weddell seals and Skuas are inhabitants of McMurdo Sound and their populations may have been affected as well
Buoyancy
In science, buoyancy or upthrust, is an upward force exerted by a fluid that opposes the weight of an immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid, thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object and this pressure difference results in a net upwards force on the object. For this reason, an object whose density is greater than that of the fluid in which it is submerged tends to sink, If the object is either less dense than the liquid or is shaped appropriately, the force can keep the object afloat. This can occur only in a reference frame, which either has a gravitational field or is accelerating due to a force other than gravity defining a downward direction. In a situation of fluid statics, the net upward force is equal to the magnitude of the weight of fluid displaced by the body.
The center of buoyancy of an object is the centroid of the volume of fluid. Archimedes principle is named after Archimedes of Syracuse, who first discovered this law in 212 B. C, more tersely, Buoyancy = weight of displaced fluid. The weight of the fluid is directly proportional to the volume of the displaced fluid. Thus, among completely submerged objects with equal masses, objects with greater volume have greater buoyancy and this is known as upthrust. Suppose a rocks weight is measured as 10 newtons when suspended by a string in a vacuum with gravity acting upon it, suppose that when the rock is lowered into water, it displaces water of weight 3 newtons. The force it exerts on the string from which it hangs would be 10 newtons minus the 3 newtons of buoyancy force,10 −3 =7 newtons. Buoyancy reduces the apparent weight of objects that have sunk completely to the sea floor and it is generally easier to lift an object up through the water than it is to pull it out of the water. The density of the object relative to the density of the fluid can easily be calculated without measuring any volumes.
Density of object density of fluid = weight weight − apparent immersed weight Example, If you drop wood into water, Example, A helium balloon in a moving car. During a period of increasing speed, the air mass inside the car moves in the direction opposite to the cars acceleration, the balloon is pulled this way. However, because the balloon is buoyant relative to the air, it ends up being pushed out of the way, If the car slows down, the same balloon will begin to drift backward. For the same reason, as the car goes round a curve and this is the equation to calculate the pressure inside a fluid in equilibrium
Ice shelf
An ice shelf is a thick floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are only found in Antarctica, Canada, the boundary between the floating ice shelf and the grounded ice that feeds it is called the grounding line. The thickness of ice shelves ranges from about 100 to 1000 meters, in contrast, sea ice is formed on water, is much thinner, and forms throughout the Arctic Ocean. It is found in the Southern Ocean around the continent of Antarctica, Ice shelves are principally driven by gravity-driven pressure from the grounded ice. That flow continually moves ice from the line to the seaward front of the shelf. The primary mechanism of mass loss from ice shelves was thought to have been iceberg calving, typically, a shelf front will extend forward for years or decades between major calving events. Snow accumulation on the surface and melting from the lower surface are important to the mass balance of an ice shelf.
Ice may accrete onto the underside of the shelf, the density contrast between glacial ice, which is denser than normal ice, and liquid water means that only about 1/9 of the floating ice is above the ocean surface. The worlds largest ice shelves are the Ross Ice Shelf and the Filchner-Ronne Ice Shelf in Antarctica, the term captured ice shelf has been used for the ice over a subglacial lake, such as Lake Vostok. All Canadian ice shelves are attached to Ellesmere Island and lie north of 82°N, Ice shelves that are still in existence are the Alfred Ernest Ice Shelf, Milne Ice Shelf, Ward Hunt Ice Shelf and Smith Ice Shelf. The MClintock Ice Shelf broke up from 1963 to 1966, the Ayles Ice Shelf broke up in 2005, a total of 74 percent of the Antarctic coastline has ice shelves attached. Their aggregate area is over 1,550,000 km2, in the last several decades, glaciologists have observed consistent decreases in ice shelf extent through melt and complete disintegration of some shelves. The Ellesmere ice shelf reduced by 90 percent in the century, leaving the separate Alfred Ernest, Milne, Ward Hunt.
A1986 survey of Canadian ice shelves found that 48 km². of ice calved from the Milne, the Ayles Ice Shelf calved entirely on August 13,2005. The Ward Hunt Ice Shelf, the largest remaining section of thick landfast sea ice along the coastline of Ellesmere Island. It further decreased by 27% in thickness between 1967 and 1999, in summer 2002, the Ward Ice Shelf experienced another major breakup. Two sections of Antarcticas Larsen Ice Shelf broke apart into hundreds of small fragments in 1995 and 2002. The breakup events may be linked to the dramatic polar warming trends that are part of global warming, the leading ideas involve enhanced ice fracturing due to surface meltwater and enhanced bottom melting due to warmer ocean water circulating under the floating ice
Density
The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can be used. Mathematically, density is defined as mass divided by volume, ρ = m V, where ρ is the density, m is the mass, and V is the volume. In some cases, density is defined as its weight per unit volume. For a pure substance the density has the numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. Thus a relative density less than one means that the floats in water. The density of a material varies with temperature and pressure and this variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object, increasing the temperature of a substance decreases its density by increasing its volume.
In most materials, heating the bottom of a results in convection of the heat from the bottom to the top. This causes it to rise relative to more dense unheated material, the reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is a property in that increasing the amount of a substance does not increase its density. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass, upon this discovery, he leapt from his bath and ran naked through the streets shouting, Eureka. As a result, the term eureka entered common parlance and is used today to indicate a moment of enlightenment, the story first appeared in written form in Vitruvius books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time, from the equation for density, mass density has units of mass divided by volume.
As there are units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per metre and the cgs unit of gram per cubic centimetre are probably the most commonly used units for density.1,000 kg/m3 equals 1 g/cm3. In industry, other larger or smaller units of mass and or volume are often more practical, see below for a list of some of the most common units of density
Brown Bluff
Brown Bluff is a basalt tuya located on the Tabarin Peninsula of northern Antarctica. It formed in the past 1 million years, which erupted subglacially within an englacial lake, the volcanos original diameter is thought to have been about 12-15 kilometers, and probably formed by a single vent. Brown Bluff is subdivided into four stages, pillow volcano, tuff cone, slope failure, the volcano is named Brown Bluff because of its steep slopes and its brown-to-black hyaloclastite. Brown Bluff has a 1.5 km long cobble and ash beach rising increasingly steeply towards towering red-brown tuff cliffs which are embedded with volcanic bombs and tephra. The cliffs are heavily eroded, resulting in loose scree and rock falls on higher slopes, permanent ice and tidewater glaciers surround the site to the north and south, occasionally filling the beach with brash ice. Lichens in the genera Xanthoria and Caloplaca have been recorded on exposed boulders from the shoreline to an elevation of 185 m, mosses occur at higher elevations near glacial drainage.
The site has been identified as an Important Bird Area by BirdLife International because it supports a colony of about 20,000 pairs of adelie. Other birds nesting there include Cape petrels, Wilsons storm petrels, weddell seals regularly haul out and leopard seals often hunt offshore. List of subglacial volcanoes Antarctic Treaty Visitor Guidelines, Brown Bluff
Terra Nova Expedition
The Terra Nova Expedition, officially the British Antarctic Expedition, was an expedition to Antarctica which took place between 1910 and 1913. It was led by Robert Falcon Scott and had various scientific, Scott wished to continue the scientific work that he had begun when leading the Discovery Expedition to the Antarctic in 1901–04. He wanted to be the first to reach the geographic South Pole and he and four companions attained the pole on 17 January 1912, where they found that the Norwegian team led by Roald Amundsen had preceded them by 34 days. Scotts entire party died on the journey from the pole, some of their bodies, journals. The expedition, named after its ship, was a private venture. It had further backing from the Admiralty, which released experienced seamen to the expedition, the expeditions team of scientists carried out a comprehensive scientific programme, while other parties explored Victoria Land and the Western Mountains. An attempted landing and exploration of King Edward VII Land was unsuccessful, a journey to Cape Crozier in June and July 1911 was the first extended sledging journey in the depths of the Antarctic winter.
For many years after his death, Scotts status as hero was unchallenged. In the final quarter of the 20th century the expedition came under closer scrutiny, the degree of Scotts personal culpability, and more recently, the culpability of certain expedition members, remain controversial. In 1909 Scott received news that Ernest Shackletons Nimrod Expedition had narrowly failed to reach the Pole and he had been forced to turn for home at 88°23 S, less than 100 geographical miles from his objective. This soured relations between the two explorers, and increased Scotts determination to surpass Shackletons achievements, as he made his preparations for a further expedition, Scott was aware of other polar ventures being planned. A Japanese expedition was being planned, the Australasian Antarctic Expedition under Douglas Mawson was to leave in 1911, Roald Amundsen, a potential rival, had announced plans for an Arctic voyage. Sixty-five men formed the shore and ships parties of the Terra Nova Expedition and they were chosen from 8,000 applicants, and included seven Discovery veterans together with five who had been with Shackleton on his 1907–09 expedition.
Lieutenant Edward Evans, who had been the officer on Morning. He abandoned plans to mount his own expedition, and transferred his financial backing to Scott. Ex-RN officer Victor Campbell, known as The Wicked Mate, was one of the few who had skills in skiing, and was chosen to lead the party that would explore King Edward VII Land. Two non-Royal Navy officers were appointed, Henry Robertson Bowers, known as Birdie, who was a lieutenant in the Royal Indian Marine, and Lawrence Oates, independently wealthy, volunteered his services to the expedition and paid £1,000 into its funds. The Admiralty provided a largely naval lower deck, including the Antarctic veterans Edgar Evans, Tom Crean, other seamen in the shore party included Patrick Keohane and Robert Forde, Thomas Clissold and Frederick Hooper
Elephant Island
Elephant Island is an ice-covered mountainous island off the coast of Antarctica in the outer reaches of the South Shetland Islands, in the Southern Ocean. Its name was given by early explorers sighting elephant seals on its shores and it is within the Antarctic claims of Argentina and the UK. Brazil has a shelter on the island, supporting the work of up to six researchers each during the summer, and another, which was dismantled in the summer of 1997/98. The island is oriented approximately east-west, with an elevation of 853 m at Pardo Ridge. Significant named features are Cape Yelcho, Cape Valentine and Cape Lookout at the northeastern and southern extremes, and Point Wild, the Endurance Glacier is the main discharge glacier. Due to slow recoveries and illegal whaling by Soviet Union with support from Japan, the island supports no significant flora or native fauna although migratory gentoo penguins and seals may be found, and chinstrap penguins nest in season. A lack of safe anchorage has prevented any permanent human settlement, despite the island being well placed to support scientific and whaling activities.
Elephant Islands name can be attributed to both its elephant head-like appearance and the sighting of elephant seals by Captain George Powell in 1821, the weather is normally foggy with much snow, and winds can reach 160 km/h. The island is most famous as the refuge of British explorer Ernest Shackleton. Following the loss of their ship Endurance in Weddell Sea ice, the first of Shackletons crew to set foot here, and presumably the first person ever to make landfall, was Perce Blackborow, originally a stowaway on Endurance. Since Blackborow was the youngest crew member, Shackleton commanded that he make the first landfall on the island, realizing that there was no chance of rescue, Shackleton decided to sail to South Georgia where he knew there were several whaling stations. Shackleton sailed with five men on a 1,287 km voyage in the open lifeboat James Caird on Easter Monday, April 24,1916. His second-in-command, Frank Wild, was left in charge of the men on Elephant Island, there was much work for the stranded men.
Because the island had no source of shelter, they constructed a shack. Blubber lamps were used for lighting, Expedition physicist Reginald James composed the following verses out of gratitude for Wilds leadership, They hunted for penguins and seals, neither of which were plentiful in autumn or winter. Many of the crew were ill and frostbitten, and they were now in danger of starvation. After four and a half months, one of the men spotted a ship on August 30,1916. The ship, with Shackleton on board, was the tug Yelcho, from Punta Arenas, commanded by Luis Pardo and it was the fourth attempt to rescue the men
RMS Titanic
Of the 2,224 passengers and crew aboard, more than 1,500 died, making it one of the deadliest commercial peacetime maritime disasters in modern history. Thomas Andrews, her architect, died in the disaster, the first class accommodation was designed to be the pinnacle of comfort and luxury, with an on-board gymnasium, swimming pool, high-class restaurants and opulent cabins. A high-power radiotelegraph transmitter was available for sending passenger marconigrams and for the operational use. Titanic only carried enough lifeboats for 1,178 people—slightly more than half of the number on board, after leaving Southampton on 10 April 1912, Titanic called at Cherbourg in France and Queenstown in Ireland before heading west to New York. On 14 April, four days into the crossing and about 375 miles south of Newfoundland, the collision caused the ships hull plates to buckle inwards along her starboard side and opened five of her sixteen watertight compartments to the sea, she could only survive four flooding.
Meanwhile and some members were evacuated in lifeboats. A disproportionate number of men were left aboard because of a women and children first protocol for loading lifeboats, at 2,20 a. m. she broke apart and foundered—with well over one thousand people still aboard. Just under two hours after Titanic sank, the Cunard liner RMS Carpathia arrived at the scene, where she brought aboard an estimated 705 survivors. The disaster was greeted with shock and outrage at the huge loss of life. Public inquiries in Britain and the United States led to improvements in maritime safety. One of their most important legacies was the establishment in 1914 of the International Convention for the Safety of Life at Sea, which still governs maritime safety today. Additionally, several new regulations were passed around the world in an effort to learn from the many missteps in wireless communications—which could have saved many more passengers. The wreck of Titanic, first discovered over 70 years after the sinking, remains on the seabed, since her discovery in 1985, thousands of artifacts have been recovered and put on display at museums around the world.
Titanic has become one of the most famous ships in history, her memory is kept alive by numerous works of culture, including books, folk songs, exhibits. Titanic is the second largest ocean liner wreck in the world, only beaten by her sister HMHS Britannic, the name Titanic was derived from Greek mythology and meant gigantic. They were by far the largest vessels of the British shipping company White Star Lines fleet, Teutonic was replaced by Olympic while Majestic was replaced by Titanic. Majestic would be back into her old spot on White Stars New York service after Titanics loss. The ships were constructed by the Belfast shipbuilders Harland and Wolff, cost considerations were relatively low on the agenda and Harland and Wolff was authorised to spend what it needed on the ships, plus a five percent profit margin
Ice calving
Ice calving, known as glacier calving or iceberg calving, is the breaking of ice chunks from the edge of a glacier. It is a form of ice ablation or ice disruption and is caused by the glacier expanding. It is the release and breaking away of a mass of ice from a glacier, ice front, ice shelf. The ice that breaks away can be classified as an iceberg, calving of glaciers is often accompanied by a loud cracking or booming sound before blocks of ice up to 60 metres high break loose and crash into the water. The entry of the ice into the water causes large, the waves formed in locations like Johns Hopkins Glacier can be so large that boats cannot approach closer than 3 kilometres. These events have become major tourist attractions in such as Alaska. Many glaciers terminate at oceans or freshwater lakes which results naturally with the calving of large numbers of icebergs, calving of Greenlands glaciers produce 12,000 to 15,000 icebergs each year alone. Calving of ice shelves is usually preceded by a rift and these events are not often observed.
Etymologically, calving is cognatic with calving as in bearing a calf and it is useful to classify causes of calving into first and third order processes. First order processes are responsible for the rate of calving at the glacier scale. The first order cause of calving is longitudinal stretching, which controls the formation of crevasses, when crevasses penetrate the full thickness of the ice, calving will occur. Longitudinal stretching is controlled by friction at the base and edges of the glacier, glacier geometry and these factors, exert the primary control on calving rate. Second and third order calving processes can be considered to be superimposed on the first order process above, melting at the waterline is an important second order calving process as it undercuts the subaerial ice, leading to collapse. Other second order processes include tidal and seismic events, buoyant forces, when calving occurs due to waterline melting, only the subaerial part of the glacier will calve, leaving a submerged foot.
Thus, a third order process is defined, whereby upward buoyant forces cause this ice foot to break off and this process is extremely dangerous, as it has been known to occur, without warning, up to 300m from the glacier terminus. Though many factors contribute to calving have been identified, a reliable predictive mathematical formula is still under development. Data is currently being assembled from ice shelves in Antarctica and Greenland to help establish a calving law, there are currently several concepts upon which to base a predictive law. Another theory, based on research, shows that the calving rate increases as a power of the spreading rate near the calving front
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