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                        Ice
                        Fro m Wikipedia, the free encyclo pedia

                           This article is about water ice. For the broader concept of "ices" as used in the planetary sciences, see volatiles. For other uses, see Ice
Navigatio n
                           (disambiguation).
Main page
                        Ice is water froz en into the solid state. It can appear transparent or opaque bluish- white color,
Co ntents               depending on the presence of impurities or air inclusions. The addition of other materials such
Featured co ntent
                        as soil may further alter the appearance.
Current events
                        Ice appears in nature in forms of snowflakes, hail, icicles, glaciers, pack ice, frost, and entire
Rando m article
                        polar ice caps. It is an important component of the global climate, and plays an important role in
Do nate to Wikipedia
                        the water cycle . Furthermore, ice has numerous cultural applications, from ice cooling of drinks to
                        winter sports and the art of ice sculpting.
Interactio n
                        The molecules in solid ice may be arranged in different ways, called phases, depending on the
Help                    temperature and pressure. Usually ice is the phase known as ice Ih , which is the most abundant           A natural block of (water) ice
Abo ut Wikipedia        of the varying solid phases on the Earth's surface. The most common phase transition to ice Ih
Co mmunity po rtal      occurs when liquid water is cooled below 0 °C (273.15 K, 32 °F) at standard atmospheric
Recent changes          pressure. It can also deposit from vapour with no intervening liquid phase, such as in the
Co ntact Wikipedia      formation of frost.
                        The word is derived from Old English īs , which in turn stems from Proto- Germanic isaz.
To o lbo x
                                      Co nt e nt s
What links here
                         1 Characteristics
Related changes
                             1.1 Slipperiness
Uplo ad file
                         2 Fo rmatio n
Special pages
                             2.1 Ice pellets
Permanent link
                              2.2 Hail
Page info rmatio n
                              2.3 Sno wflakes
Cite this page
                              2.4 Diamo nd dust
                         3 Pro ductio n
Print/expo rt                3.1 Ice harvesting

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Create a bo o k           3.2 Co mmercial pro ductio n                                                                        Snowflakes (ice crystals) by Wilson
Do wnlo ad as PDF     4 Uses                                                                                                  Bentley, 1902
Printable versio n        4.1 Spo rts
                          4.2 Other uses
                      5 Ice and transpo rtatio n
Languages
                      6 Phases
Afrikaans             7 Other ices
Alemannisch           8 See also
Ænglisc               9 References
‫اﻟﻌرﺑﯾ ﺔ‬              10 External links
Arago nés
                     Characteristics                                                                                                                                [edit]
Asturianu
Avañe'ẽ                                                        As a naturally occurring crystalline inorganic solid with an ordered structure, ice is considered a
Aymar aru                                                      mineral.[1] It possesses a regular crystalline structure based on the molecule of water, which
Azərbaycanca                                                   consists of a single oxygen atom covalently bonded to two hydrogen atoms, or H- O- H.
বাংলা                                                          However, many of the physical properties of water and ice are controlled by the formation of
Беларуская                                                     hydrogen bonds between adjacent oxygen and hydrogen atoms. It is a weak bond, but is critical
Беларуская                                                     in controlling the structure of both water and ice.
(тарашкевіца)
                                                               An unusual property of ice froz en at atmospheric pressure is that the solid is approximately
Български
                                                               8.3% less dense than liquid water. The density of ice is 0.9167 g/cm³ at 0 °C, whereas water
Bo sanski
                                                               has a density of 0.9998 g/cm³ at the same temperature. Liquid water is densest, essentially 1.00
Català
                                                               g/cm³, at 4 °C and becomes less dense as the water molecules begin to form the hexagonal
Чӑвашла
                      Crystal structure of hexagonal ice.      crystals [2] of ice as the freez ing point is reached. This is due to hydrogen bonding dominating
Česky
                      Grey dashed lines indicate hydrogen      the intermolecular forces, which results in a packing of molecules less compact in the solid.
Cymraeg               bonds.                                   Density of ice increases slightly with decreasing temperature and has a value of 0.9340 g/cm³
Dansk
                                                               at −180 °C (93 K).[3]
Deitsch
Deutsch              The effect of expansion during freez ing can be dramatic, and is a basic cause of freez e- thaw weathering of rock in nature. It is also a
Diné bizaad          common cause of the flooding of houses when water pipes burst due to the pressure of expanding water when it freez es, then leak water
Eesti                after thawing.
Ελληνικά             The result of this process is that ice (in its most common form) floats on liquid water, which is an important feature in Earth's biosphere. It
Españo l             has been argued that without this property natural bodies of water would freez e, in some cases permanently, from the bottom up, [4]
Esperanto            resulting in a loss of bottom- dependent animal and plant life in fresh and sea water. Sufficiently thin ice sheets allow light to pass through
Euskara              while protecting the underside from short- term weather extremes such as wind chill. This creates a sheltered environment for bacterial and
‫ﻓﺎرﺳﯽ‬                algal colonies. When sea water freez es, the ice is riddled with brine- filled channels which sustain sympagic organisms such as bacteria,
Français             algae, copepods and annelids, which in turn provide food for animals such as krill and specialised fish like the Bald notothen, fed upon in
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Gaeilge             turn by larger animals such as Emperor penguins and Minke whales.[5]
Gàidhlig
                    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,
Galego
                    the temperature remains constant at 0 °C. While melting, any energy added breaks the hydrogen bonds between ice (water) molecules.
한국어
                    Energy becomes available to increase the thermal energy (temperature) only after enough hydrogen bonds are broken that the ice can
Հայերեն
                    be considered liquid water. The amount of energy consumed in breaking hydrogen bonds in the transition from ice to water is known as
िह दी
                    the heat of fusion .
Hrvatski
Ido                 As with water, ice absorbs light at the red end of the spectrum preferentially as the result of an overtone of an oxygen- hydrogen (O- H)
Bahasa Indo nesia   bond stretch. Compared with water, this absorption is shifted toward slightly lower energies. Thus, ice appears blue, with a slightly greener
Interlingua         tint than for liquid water. Since absorption is cumulative, the color effect intensifies with increasing thickness or if internal reflections cause
Iñupiak             the light to take a longer path through the ice.[6]
IsiZulu             Other colors can appear in the presence of light absorbing impurities, where the impurity is dictating the color rather than the ice itself. For
Íslenska            instance, icebergs containing impurities (e.g., sediments, algae, air bubbles) can appear brown, grey or green.[6]
Italiano
‫ע ברית‬              Slipperiness                                                                                                                                     [edit]
Basa Jawa           It has long been believed that ice is slippery because the pressure of an object in contact with it
ქართული             causes a thin layer to melt. For example, the blade of an ice skate, exerting pressure on the ice,
Қазақша             melts a thin layer, providing lubrication between the ice and the blade. This explanation, called
Kiswahili           "pressure melting", originated in 19th century. This however did not account for skating on ice
Kreyò l ayisyen     temperatures lower than - 3.5 °C, whereas skaters often skate on lower temperature ice. In 20th
Latina              century an alternative explanation, called "friction heating" was proposed, whereby friction of the
Latviešu            material was causing the ice layer melting. However, this theory also failed to explain skating at
Lietuvių            low temperature. In fact, neither explanation explained why ice is slippery when standing still
Lingála             even at below- z ero temperatures.[7]
                                                                                                                                Froz en waterfall in southeast New
Magyar
                    This explanation has come into doubt with the proposal that ice molecules in contact with air          York
Македо нски
                    cannot properly bond with the molecules of the mass of ice beneath (and thus are free to move
Malagasy
                    like molecules of liquid water). These molecules remain in a semiliquid state, providing lubrication regardless of pressure against the ice
मराठी
                    exerted by any object.[8]
Bahasa Melayu
Мо кшень
                    Formation                                                                                                                                        [edit]
Мо нго л
Nāhuatl             Ice that is found at sea may be in the form of sea ice, pack ice, or icebergs. The term that
Nederlands          collectively describes all of the parts of the Earth's surface where water is in froz en form is the
日本語                 cryosphere. Ice is an important component of the global climate, particularly in regard to the
No rsk (bo kmål)    water cycle. Glaciers and snowpacks are an important storage mechanism for fresh water; over
No rsk (nyno rsk)   time, they may sublimate or melt. Snowmelt is often an important source of seasonal fresh water.
No uo rmand
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No uo rmand
                    Rime is a type of ice formed on cold objects when drops of water crystalliz e on them. This can
Occitan
                    be observed in foggy weather, when the temperature drops during the night. Soft rime contains a
Oʻzbekcha
                    high proportion of trapped air, making it appear white rather than transparent, and giving it a
Plattdüütsch
                    density about one quarter of that of pure ice. Hard rime is comparatively denser.                         Feather ice on the plateau near Alta,
Po lski
                                                                                                                              Norway. The crystals form at
Po rtuguês          Aufeis is layered ice that forms in Arctic and subarctic stream valleys. Ice, froz en in the stream
                                                                                                                              temperatures below −30 °C (i.e. −22 °F).
Ro mână             bed, blocks normal groundwater discharge, and causes the local water table to rise, resulting in
Runa Simi           water discharge on top of the froz en layer. This water then freez es, causing the water table to
Русский             rise further and repeat the cycle. The result is a stratified ice deposit, often several meters thick.
Саха тыла           Ice can also form icicles, similar to stalactites in appearance, or stalagmite- like forms as water drips and re- freez es.
Shqip
                    Clathrate hydrates are forms of ice that contain gas molecules trapped within its crystal lattice.
Sicilianu
Simple English
                    Pancake ice is a formation of ice generally created in areas with less calm conditions.
Slo venčina         Candle Ice is a form of Rotten Ice that develops in columns perpendicular to the surface of a lake.
Slo venščina
                    Ice discs are circular formations of ice surrounded by water in a river.
So o maaliga
                    The World Meteorological Organiz ation defines several kinds of ice depending on origin, siz e, shape, influence and so on. [9]
Српски / srpski
Srpsko hrvatski /
српско хрватски     Ice pellets                                                                                                                                   [edit]
Basa Sunda             See also: Ice pellets
Suo mi
                    Ice pellets are a form of precipitation consisting of small, translucent balls of ice. This form of
Svenska
                    precipitation is also known as sleet .[10] Ice pellets are usually (but not always) smaller than
Tagalo g
                    hailstones.[11] They often bounce when they hit the ground, and generally do not freez e into a
   లుగు
                    solid mass unless mixed with freez ing rain. The METAR code for ice pellets is PL.[12]
ไทย
То ҷ икӣ
                    Ice pellets form when a layer of above- freez ing air is located between 1,500 metres (4,900 ft)
ᏣᎳᎩ
                    and 3,000 metres (9,800 ft) above the ground, with sub- freez ing air both above and below it.
Tsetsêhestâhese
                    This causes the partial or complete melting of any snowflakes falling through the warm layer. As
Türkçe
                    they fall back into the sub- freez ing layer closer to the surface, they re- freez e into ice pellets.
Українська
                    However, if the sub- freez ing layer beneath the warm layer is too small, the precipitation will not
‫اردو‬
                    have time to re- freez e, and freez ing rain will be the result at the surface. A temperature profile     An accumulation of ice pellets

Vèneto
                    showing a warm layer above the ground is most likely to be found in advance of a warm front
Tiếng Việt
                    during the cold season, [13] but can occasionally be found behind a passing cold front.
Walo n
                    Hail                                                                                                                                          [edit]
Winaray
‫יי ִדיש‬                See also: Hail
粵語                  Like other precipitation, hail forms in storm clouds when supercooled water droplets freez e on
Zazaki
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Zazaki       contact with condensation nuclei, such as dust or dirt. The storm's updraft blows the hailstones to
Žemaitėška   the upper part of the cloud. The updraft dissipates and the hailstones fall down, back into the
中文           updraft, and are lifted up again. Hail has a diameter of 5 millimetres (0.20 in) or more.[14] Within
த            METAR code, GR is used to indicate larger hail, of a diameter of at least 6.4 millimetres
             (0.25 in) and GS for smaller.[12] Stones just larger than golf ball- siz ed are one of the most
             frequently reported hail siz es.[15] Hailstones can grow to 15 centimetres (6 in) and weigh more
             than .5 kilograms (1.1 lb).[16] In large hailstones, latent heat released by further freez ing may
             melt the outer shell of the hailstone. The hailstone then may undergo 'wet growth', where the             A large hailstone, about 6 cm (2.36
             liquid outer shell collects other smaller hailstones.[17] The hailstone gains an ice layer and            in) in diameter
             grows increasingly larger with each ascent. Once a hailstone becomes too heavy to be
             supported by the storm's updraft, it falls from the cloud.[18]
             Hail forms in strong thunderstorm clouds, particularly those with intense updrafts, high liquid water content, great vertical extent, large water
             droplets, and where a good portion of the cloud layer is below freez ing 0 °C (32 °F).[14] Hail- producing clouds are often identifiable by
             their green coloration.[19][20] The growth rate is maximiz ed at about −13 °C (9 °F), and becomes vanishingly small much below −30 °C
             (−22 °F) as supercooled water droplets become rare. For this reason, hail is most common within continental interiors of the mid- latitudes,
             as hail formation is considerably more likely when the freez ing level is below the altitude of 11,000 feet (3,400 m).[21] Entrainment of dry
             air into strong thunderstorms over continents can increase the frequency of hail by promoting evaporational cooling which lowers the
             freez ing level of thunderstorm clouds giving hail a larger volume to grow in. Accordingly, hail is actually less common in the tropics
             despite a much higher frequency of thunderstorms than in the mid- latitudes because the atmosphere over the tropics tends to be warmer
             over a much greater depth. Hail in the tropics occurs mainly at higher elevations.[22]

             Snowflakes                                                                                                                                      [edit]
                Main article: Snowflake
             Snow crystals form when tiny supercooled cloud droplets (about 10 μm in diameter) freez e.
             These droplets are able to remain liquid at temperatures lower than −18 °C (255 K; −0 °F),
             because to freez e, a few molecules in the droplet need to get together by chance to form an
             arrangement similar to that in an ice lattice; then the droplet freez es around this "nucleus."
             Experiments show that this "homogeneous" nucleation of cloud droplets only occurs at
             temperatures lower than −35 °C (238 K; −31 °F).[23] In warmer clouds an aerosol particle or "ice
             nucleus" must be present in (or in contact with) the droplet to act as a nucleus. Our
             understanding of what particles make efficient ice nuclei is poor — what we do know is they are
             very rare compared to that cloud condensation nuclei on which liquid droplets form. Clays,
             desert dust and biological particles may be effective, [24] although to what extent is unclear.
             Artificial nuclei are used in cloud seeding.[25] The droplet then grows by condensation of water
             vapor onto the ice surfaces.
                                                                                                                       Snowflake viewed in an optical
                                                                                                                       microscope

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                                                                                                        microscope
Diamond dust                                                                                   [edit]

   See also: Diamond dust
Diamond dust, also known as ice needles or ice crystals, forms at temperatures approaching −40 °C (−40 °F) due to air with slightly
higher moisture from aloft mixing with colder, surface based air.[26] The METAR identifier for diamond dust within international hourly
weather reports is IC.[12]

Production                                                                                                                                  [edit]

Ice is now mechanically produced on a large scale, but before refrigeration was developed ice
was harvested from natural sources for human use.

Ice harvesting                                                                                 [edit]

   Main article: Ice cutting
Ice has long been valued as a means of cooling. In 400 BC Iran, Persian engineers had already
mastered the technique of storing ice in the middle of summer in the desert. The ice was brought
in during the winters from nearby mountains in bulk amounts, and stored in specially designed,
naturally cooled refrigerators, called yakhchal (meaning ice storage). This was a large
underground space (up to 5000 m³) that had thick walls (at least two meters at the base) made           Harvesting ice on Lake Saint Clair in
of a special mortar called sārooj, composed of sand, clay, egg whites, lime, goat hair, and ash         Michigan, c. 1905
in specific proportions, and which was known to be resistant to heat transfer. This mixture was
thought to be completely water impenetrable. The space often had access to a qanat, and often
contained a system of windcatchers which could easily bring temperatures inside the space
down to frigid levels on summer days. The ice was used to chill treats for royalty.
There were thriving industries in 16/17th century England whereby low lying areas along the
Thames estuary were flooded during the winter, and ice harvested in carts and stored inter-
seasonally in insulated wooden houses as a provision to an icehouse often located in large
country houses, and widely used to keep fish fresh when caught in distant waters. This was
allegedly copied by an Englishman who had seen the same activity in China.[27] Ice was
imported into England from Norway on a considerable scale as early as 1823.[28]
In the United States, the first cargo of ice was sent from New York City to Charleston, South
Carolina in 1799, [28] and by the first half of the 19th century, ice harvesting had become big         B&W film of 1919 ice harvest at
business. Frederic Tudor, who became known as the “Ice King,” worked on developing better               Pocono Manor in the Poconos
insulation products for the long distance shipment of ice, especially to the tropics; this became
known as the ice trade.
Trieste sent ice to Egypt, Corfu, and Zante; Switz erland sent it to France; and Germany
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sometimes was supplied from Bavarian lakes.[28] Until recently, [when?] the Hungarian Parliament
building used ice harvested in the winter from Lake Balaton for air conditioning.
Icehouses were used to store ice formed in the winter, to make ice available all year long, and
early refrigerators were known as iceboxes, because they had a block of ice in them. In many
cities, it was not unusual to have a regular ice delivery service during the summer. The advent of
artificial refrigeration technology has since made delivery of ice obsolete.
Ice is still harvested for ice and snow sculpture events . A swing saw is used to get ice for the
                                                                                                         An ice manufacturing plant in East
Harbin International Ice and Snow Sculpture Festival each year from the froz en surface of the
                                                                                                         Midnapore, India
Songhua River.[29] Many ice sculptures are made from the ice.

Commercial production                                                                           [edit]
Ice is now produced on an industrial scale, for uses including food storage and processing, chemical manufacturing, concrete mixing and
curing, and consumer or packaged ice.[30] Most commercial ice makers produce three basic types of fragmentary ice: flake, tubular and
plate, using a variety of techniques.[30] Large batch ice makers can produce up to 75 tons of ice per day. [31]
Ice production is a large business; in 2002, there were 426 commercial ice- making companies in the United States, with a combined
value of shipments of $595,487,000.[32]
For small- scale ice production, many modern home refrigerators can also make ice with a built in icemaker, which will typically make ice
cubes or crushed ice. Stand- alone icemaker units that make ice cubes are often called ice machines.

Uses                                                                                                                                          [edit]


Sports                                                                                                                                        [edit]

Ice also plays a central role in winter recreation and in many sports such as ice skating, tour
skating, ice hockey, ice fishing, ice climbing, curling, broomball and sled racing on bobsled,
luge and skeleton. Many of the different sports played on ice get international attention every
four years during the Winter Olympic Games .
A sort of sailboat on blades gives rise to ice yachting. The human quest for excitement has
even led to ice racing, where drivers must speed on lake ice, while also controlling the skid of
their vehicle (similar in some ways to dirt track racing ). The sport has even been modified for ice
rinks.
                                                                                                         Ice sailing on the Żnin Small Lake
Other uses                                                                                      [edit]

   Ice cubes or crushed ice can be used to cool drinks. As the ice melts, it absorbs heat and
   keeps the drink near 0 °C (32 °F).

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   Ice can be used to reduce swelling (by decreasing blood flow) and pain by pressing it against an area of the body. [33]
   Engineers used formidable strength of pack ice when they constructed Antarctica's first
   floating ice pier in 1973.[34] Such ice piers are used during cargo operations to load and
   offload ships. Fleet operations personnel make the floating pier during the winter. They build
   upon naturally- occurring froz en seawater in McMurdo Sound until the dock reaches a depth
   of about 22 feet (6.7 m). Ice piers have a lifespan of three to five years.
   Structures and ice sculptures are built out of large chunks of ice. The structures are mostly
   ornamental (as in the case with ice castles), and not practical for long- term habitation. Ice
   hotels exist on a seasonal basis in a few cold areas. Igloos are another example of a
   temporary structure, made primarily from snow.
                                                                                                               Ice pier during 1983 cargo
   During World War II, Project Habbakuk was a British programme which investigated the use                    operations. McMurdo Station, Antarctica
   of pykrete (wood fibers mixed with ice) as a possible material for warships, especially aircraft
   carriers, due to the ease with which a large deck could be constructed, but the idea was
   given up when there were not enough funds for construction of a prototype.
   Ice can be used to start a fire by carving it into a lens which will focus sunlight onto kindling. A fire will eventually start. [35]
   Ice has even been used as the material for a variety of musical instruments, for example by percussionist Terje Isungset.[36]
   Ice was once used to cool refrigerators in the 19th century, which is reflected in the name "iceboxes."
   Ice can be used as part of an air conditioning system.

Ice and transportation                                                                                                                            [edit]

Ice can also be an obstacle; for harbors near the poles, being ice- free is an important
advantage; ideally, all year long. Examples are Murmansk (Russia), Petsamo (Russia, formerly
Finland) and Vardø (Norway). Harbors which are not ice- free are opened up using icebreakers.
Ice forming on roads is a dangerous winter haz ard. Black ice is very difficult to see, because it
lacks the expected frosty surface. Whenever there is freez ing rain or snow which occurs at a
temperature near the melting point, it is common for ice to build up on the windows of vehicles.
Driving safely requires the removal of the ice build- up. Ice scrapers are tools designed to break
the ice free and clear the windows, though removing the ice can be a long and laborious
process.
                                                                                                          U.S. Coast Guard icebreakers near
Far enough below the freez ing point, a thin layer of ice crystals can form on the inside surface of
                                                                                                          McMurdo Station, February 2002
windows. This usually happens when a vehicle has been left alone after being driven for a while,
but can happen while driving, if the outside temperature is low enough. Moisture from the driver's
breath is the source of water for the crystals. It is troublesome to remove this form of ice, so people often open their windows slightly when
the vehicle is parked in order to let the moisture dissipate, and it is now common for cars to have rear- window defrosters to solve the
problem. A similar problem can happen in homes, which is one reason why many colder regions require double- pane windows for

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insulation.
When the outdoor temperature stays below freez ing for extended periods, very thick layers of ice can form on lakes and other bodies of
water, although places with flowing water require much colder temperatures. The ice can become thick enough to drive onto with
automobiles and trucks. Doing this safely requires a thickness of at least 30 cm (one foot).
For ships, ice presents two distinct haz ards. Spray and freez ing rain can produce an ice build- up on the superstructure of a vessel
sufficient to make it unstable, and to require it to be hacked off or melted with steam hoses. And icebergs — large masses of ice floating
in water (typically created when glaciers reach the sea) — can be dangerous if struck by a ship when underway. Icebergs have been
responsible for the sinking of many ships, the most famous probably being the Titanic.
For aircraft, ice can cause a number of dangers. As an aircraft climbs, it passes through air
layers of different temperature and humidity, some of which may be conducive to ice formation. If
ice forms on the wings or control surfaces, this may adversely affect the flying qualities of the
aircraft. During the first non- stop flight of the Atlantic, the British aviators Captain John Alcock and
Lieutenant Arthur Whitten Brown encountered such icing conditions – Brown left the cockpit and
climbed onto the wing several times to remove ice which was covering the engine air intakes of
the Vickers Vimy aircraft they were flying.
A particular icing vulnerability associated with reciprocating internal combustion engines is the
carburetor. As air is sucked through the carburetor into the engine, the local air pressure is
lowered, which causes adiabatic cooling. So, in humid near- freez ing conditions, the carburetor
will be colder, and tend to ice up. This will block the supply of air to the engine, and cause it to
fail. For this reason, aircraft reciprocating engines with carburetors are provided with carburetor
air intake heaters. The increasing use of fuel injection—which does not require carburetors—has
made "carb icing" less of an issue for reciprocating engines.
Jet engines do not experience carb icing, but recent evidence indicates that they can be
slowed, stopped, or damaged by internal icing in certain types of atmospheric conditions much
                                                                                                            Ice formation on window glass of
more easily than previously believed. In most cases, the engines can be quickly restarted and               high altitude flying airplane
flights are not endangered, but research continues to determine the exact conditions which
produce this type of icing, and find the best methods to prevent, or reverse it, in flight.

Phases                                                                                                                                         [edit]

Ice may be any one of the 15 known solid phases of water.
Most liquids under increased pressure freez e at higher temperatures because the
pressure helps to hold the molecules together. However, the strong hydrogen bonds
in water make it different: water, under a pressure higher than 1 atm (0.10 MPa),
freez es at a temperature below 0 °C. The melting of ice under high pressures is

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thought to contribute to the movement of glaciers.
Ice, water, and water vapour can coexist at the triple point, which is exactly 0.01 °C
(273.16 K) at a pressure of 611.73 Pa (the Kelvin is in fact defined as 1/273.16 of
the difference between this triple point and absolute z ero).[37] Unlike most other
solids, ice is difficult to superheat. In an experiment, ice at −3 °C was superheated
to about 17 °C for about 250 picoseconds.[38]
Subjected to higher pressures and varying temperatures, ice can form in fifteen
separate known phases. With care all these phases except ice X can be
                                                                                           Pressure dependence of ice melting.
recovered at ambient pressure and low temperature. The types are differentiated
by their crystalline structure, ordering and density. There are also two metastable
phases of ice under pressure, both fully hydrogen- disordered; these are IV and XII. Ice XII was discovered in 1996. In 2006, XIII and XIV
were discovered.[39] Ices XI, XIII, and XIV are hydrogen- ordered forms of ices I h , V, and XII respectively. In 2009, ice XV was found at
extremely high pressures and −143 °C.[40] At even higher pressures, ice is predicted to become a metal; this has been variously
estimated to occur at 1.55 TPa [41] or 5.62 TPa. [42]
As well as crystalline forms, solid water can exist in amorphous states as amorphous solid water (ASW), low- density amorphous ice
(LDA), high- density amorphous ice (HDA), very high- density amorphous ice (VHDA) and hyperquenched glassy water (HGW).
In outer space, hexagonal crystalline ice (the predominant form found on Earth) is extremely rare. Amorphous ice is more common;
however, hexagonal crystalline ice can be formed via volcanic action.[43]




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    Log- lin pressure- temperature phase diagram of water. The Roman numerals correspond to some ice phases listed below.


Phase                                                             Charact erist ics
        Amorphous ice is an ice lacking crystal structure. Amorphous ice exists in three forms: low- density (LDA) formed at

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          atmospheric pressure, or below, high density (HDA) and very high density amorphous ice (VHDA), forming at higher
Amorphous
          pressures. LDA forms by extremely quick cooling of liquid water ("hyperquenched glassy water", HGW), by depositing water
ice
          vapour on very cold substrates ("amorphous solid water", ASW) or by heating high density forms of ice at ambient pressure
          ("LDA").
           Normal hexagonal crystalline ice. Virtually all ice in the biosphere is ice Ih , with the exception only of a small amount of ice
Ice Ih
           Ic .
           A metastable cubic crystalline variant of ice. The oxygen atoms are arranged in a diamond structure. It is produced at
Ice Ic     temperatures between 130 and 220 K, and can exist up to 240 K, [44][45] when it transforms into ice I h . It may occasionally
           be present in the upper atmosphere.[46]
           A rhombohedral crystalline form with highly ordered structure. Formed from ice Ih by compressing it at temperature of 190
Ice II
           –210 K. When heated, it undergoes transformation to ice III.
           A tetragonal crystalline ice, formed by cooling water down to 250 K at 300 MPa. Least dense of the high- pressure phases.
Ice III
           Denser than water.
           A metastable rhombohedral phase. It can be formed by heating high- density amorphous ice slowly at a pressure of
Ice IV
           810 MPa. It doesn't form easily without a nucleating agent.[47]
           A monoclinic crystalline phase. Formed by cooling water to 253 K at 500 MPa. Most complicated structure of all the
Ice V
           phases.[48]
Ice VI     A tetragonal crystalline phase. Formed by cooling water to 270 K at 1.1 GPa. Exhibits Debye relaxation.[49]
           A cubic phase. The hydrogen atoms' positions are disordered. Exhibits Debye relaxation. The hydrogen bonds form two
Ice VII
           interpenetrating lattices.
           A more ordered version of ice VII, where the hydrogen atoms assume fixed positions. Formed from ice VII, by cooling it
Ice VIII
           below 5 °C (278 K).
           A tetragonal phase. Formed gradually from ice III by cooling it from 208 K to 165 K, stable below 140 K and pressures
Ice IX
           between 200 MPa and 400 MPa. It has density of 1.16 g/cm3, slightly higher than ordinary ice.
Ice X      Proton- ordered symmetric ice. Forms at about 70 GPa. [50]
           An orthorhombic, low- temperature equilibrium form of hexagonal ice. It is ferroelectric. Ice XI is considered the most stable
Ice XI     configuration of ice Ih . The natural transformation process is very slow and ice XI has been found in Antarctic ice 100 to
           10,000 years old. That study indicated that the temperature below which ice XI forms is −36 °C (240 K).[51]
           A tetragonal, metastable, dense crystalline phase. It is observed in the phase space of ice V and ice VI. It can be prepared
Ice XII    by heating high- density amorphous ice from 77 K to about 183 K at 810 MPa. It has a density of 1.3 g cm−3 at 127 K (i.e.,
           approximately 1.3 times more dense than water).
Ice XIII   A monoclinic crystalline phase. Formed by cooling water to below 130 K at 500 MPa. The proton- ordered form of ice V. [52]
Ice XIV    An orthorhombic crystalline phase. Formed below 118 K at 1.2 GPa. The proton- ordered form of ice XII. [52]
                                                                                                                                   PDFmyURL.com
Ice XV        The proton- ordered form of ice VI formed by cooling water to around 80–108 K at 1.1 GPa.


Other ices                                                                                                                                               [edit]

   Main article: Volatiles
The solid phases of several other volatile substances are also referred to as ices; generally a
volatile is classed as an ice if its melting point lies above ~ 100 K. The best known example is
dry ice, the solid form of carbon dioxide.
A "magnetic analogue" of ice is also realiz ed in some insulating magnetic materials in which the
magnetic moments mimic the position of protons in water ice and obey energetic constraints
similar to the Bernal- Fowler ice rules arising from the geometrical frustration of the proton
configuration in water ice. These materials are called spin ice.

See also                                                                                                    [edit]

   Density of ice versus water                                                                                        Detail of an ice cube
   Ice climbing
   Ice famine
   Pumpable ice technology

References                                                                                                                                               [edit]

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         ab
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External links                                                                                                                                                               [edit]

  The National Snow and Ice Data Center                     , based in the United States
                                                                                                                                                 Look up ice in Wiktionary, the
  The phase diagram of water, including the ice variants                                                                                         free dictionary.
  Webmineral listing for Ice
  MinDat.org listing and location data for Ice
                                                                                                                                                Wikimedia Commons has media
  The physics of ice                                                                                                                            related to: Ice
  The phase diagrams of water with some high pressure diagrams
  'Unfreez able' water, 'bound water' and water of hydration
  Electromechanical properties of ice
  Estimating the maximum thickness of an ice layer
  Sandia's Z machine creates ice in nanoseconds
  Amaz ing ice at Lac Leman
  The Surprisingly Cool History of Ice

 V · T· E ·                                                                                           Ice
 C ryst alline f o rms o f ice     Ih · Ic · II · III · IV · V · VI · VII · VIII · IX · X · XI · XII · XIII · XIV · XV ·

                                   Amorphous solid water · Anchor ice · Black ice · Diamond dust · Drift ice · Firn · Fraz il ice · Frost flowers · Glacier ·
              Ice f o rmat io ns
                                   Iceberg · Icicle · Ice circle / Ice disc · Ice crystals · Ice nucleus · Ice spike · Névé · Needle ice · Sea ice · Slurry ice ·

                                                                                                                                                                      PDFmyURL.com
                    Ice Ag e s     Little Ice Age · Pleistocene ·

                                   Curling · Figure skating · Ice skating · Ice hockey · Ice blocking · Ice boating · Ice fishing · Icebiking · Ice climbing ·
                   Ice sp o rt s
                                   Tour skating ·
                        O t he r   Ice hotel · Ice cream · Ice cube · Pykrete ·


 Categories: Water ice         Glaciology      Minerals     Transparent materials



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