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84-459: Ice is the solid form of water. Ice or ICE may also refer to: Ice Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C , 32 ° F , or 273.15 K . It occurs naturally on Earth , on other planets, in Oort cloud objects, and as interstellar ice . As a naturally occurring crystalline inorganic solid with an ordered structure, ice

168-412: A force or "weight" of about 10.1 newtons , resulting in a pressure of 10.1 N/cm or 101   kN /m (101 kilopascals, kPa). A column of air with a cross-sectional area of 1   in would have a weight of about 14.7   lbf , resulting in a pressure of 14.7   lbf/in . Atmospheric pressure is caused by the gravitational attraction of the planet on the atmospheric gases above the surface and

252-619: A density between a quarter and two thirds that of pure ice, due to a high proportion of trapped air, which also makes soft rime appear white. Hard rime is denser, more transparent, and more likely to appear on ships and aircraft. Cold wind specifically causes what is known as advection frost when it collides with objects. When it occurs on plants, it often causes damage to them. Various methods exist to protect agricultural crops from frost - from simply covering them to using wind machines. In recent decades, irrigation sprinklers have been calibrated to spray just enough water to preemptively create

336-415: A diurnal or semidiurnal (twice-daily) cycle caused by global atmospheric tides . This effect is strongest in tropical zones, with an amplitude of a few hectopascals, and almost zero in polar areas. These variations have two superimposed cycles, a circadian (24 h) cycle, and a semi-circadian (12 h) cycle. The highest adjusted-to-sea level barometric pressure ever recorded on Earth (above 750 meters)

420-410: 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 freezes around this "nucleus". Experiments show that this "homogeneous" nucleation of cloud droplets only occurs at temperatures lower than −35 °C (238 K; −31 °F). In warmer clouds an aerosol particle or "ice nucleus" must be present in (or in contact with)

504-704: A form of precipitation consisting of small, translucent balls of ice, which are usually smaller than hailstones. This form of precipitation is also referred to as "sleet" by the United States National Weather Service . (In British English "sleet" refers to a mixture of rain and snow .) Ice pellets typically form alongside freezing rain, when a wet warm front ends up between colder and drier atmospheric layers. There, raindrops would both freeze and shrink in size due to evaporative cooling. So-called snow pellets, or graupel , form when multiple water droplets freeze onto snowflakes until

588-436: A function of altitude can be approximated as constant and contributes little to this fall-off. Pressure measures force per unit area, with SI units of pascals (1 pascal = 1 newton per square metre , 1   N/m ). On average, a column of air with a cross-sectional area of 1 square centimetre (cm ), measured from the mean (average) sea level to the top of Earth's atmosphere, has a mass of about 1.03 kilogram and exerts

672-559: A function of temperature and sliding speed. 2014 research suggests that frictional heating is the most important process under most typical conditions. The term that collectively describes all of the parts of the Earth's surface where water is in frozen form is the cryosphere . Ice is an important component of the global climate, particularly in regard to the water cycle. Glaciers and snowpacks are an important storage mechanism for fresh water; over time, they may sublimate or melt. Snowmelt

756-432: A hailstone becomes too heavy to be supported by the storm's updraft, it falls from the cloud. 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 freezing 0 °C (32 °F). Hail-producing clouds are often identifiable by their green coloration. The growth rate

840-581: A key role in Earth's water cycle and climate . In the recent decades, ice volume on Earth has been decreasing due to climate change . The largest declines have occurred in the Arctic and in the mountains located outside of the polar regions. The loss of grounded ice (as opposed to floating sea ice ) is the primary contributor to sea level rise . Humans have been using ice for various purposes for thousands of years. Some historic structures designed to hold ice to provide cooling are over 2,000 years old. Before

924-419: A layer of ice that would form slowly and so avoid a sudden temperature shock to the plant, and not be so thick as to cause damage with its weight. Ablation of ice refers to both its melting and its dissolution . The melting of ice entails the breaking of hydrogen bonds between the water molecules. The ordering of the molecules in the solid breaks down to a less ordered state and the solid melts to become

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1008-456: A liquid. This is achieved by increasing the internal energy of the ice beyond the melting point . When ice melts it absorbs as much energy as would be required to heat an equivalent amount of water by 80 °C. While melting, the temperature of the ice surface remains constant at 0 °C. The rate of the melting process depends on the efficiency of the energy exchange process. An ice surface in fresh water melts solely by free convection with

1092-410: A location on Earth 's surface ( terrain and oceans ). It is directly proportional to the mass of air over that location. For numerical reasons, atmospheric models such as general circulation models (GCMs) usually predict the nondimensional logarithm of surface pressure . The average value of surface pressure on Earth is 985 hPa. This is in contrast to mean sea-level pressure, which involves

1176-436: A low speed. Ice forms on calm water from the shores, a thin layer spreading across the surface, and then downward. Ice on lakes is generally four types: primary, secondary, superimposed and agglomerate. Primary ice forms first. Secondary ice forms below the primary ice in a direction parallel to the direction of the heat flow. Superimposed ice forms on top of the ice surface from rain or water which seeps up through cracks in

1260-427: A pressure of about 2 atmospheres (1 atm of air plus 1 atm of water). Conversely, 10.3 m is the maximum height to which water can be raised using suction under standard atmospheric conditions. Low pressures, such as natural gas lines, are sometimes specified in inches of water , typically written as w.c. (water column) gauge or w.g. (inches water) gauge. A typical gas-using residential appliance in

1344-505: A rate that depends linearly on the water temperature, T ∞ , when T ∞ is less than 3.98 °C, and superlinearly when T ∞ is equal to or greater than 3.98 °C, with the rate being proportional to (T ∞  − 3.98 °C) , with α  =  ⁠ 5 / 3 ⁠ for T ∞ much greater than 8 °C, and α =  ⁠ 4 / 3 ⁠ for in between temperatures T ∞ . In salty ambient conditions, dissolution rather than melting often causes

1428-487: A single oxygen atom covalently bonded to two hydrogen atoms , or H–O–H. However, many of the physical properties of water and ice are controlled by the formation of hydrogen bonds between adjacent oxygen and hydrogen atoms; while it is a weak bond, it is nonetheless critical in controlling the structure of both water and ice. An unusual property of water is that its solid form—ice frozen at atmospheric pressure —is approximately 8.3% less dense than its liquid form; this

1512-746: A soft ball-like shape is formed. So-called " diamond dust ", (METAR code IC ) 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. As water drips and re-freezes, it can form hanging icicles , or stalagmite -like structures on the ground. On sloped roofs, buildup of ice can produce an ice dam , which stops melt water from draining properly and potentially leads to damaging leaks. More generally, water vapor depositing onto surfaces due to high relative humidity and then freezing results in various forms of atmospheric icing , or frost . Inside buildings, this can be seen as ice on

1596-424: A standard lapse rate) associated with reduction of sea level from high elevations. The Dead Sea , the lowest place on Earth at 430 metres (1,410 ft) below sea level, has a correspondingly high typical atmospheric pressure of 1,065   hPa. A below-sea-level surface pressure record of 1,081.8 hPa (31.95 inHg) was set on 21 February 1961. The lowest non-tornadic atmospheric pressure ever measured

1680-471: A temperature of −78.5 °C (−109.3 °F), the vaporization point of solid carbon dioxide (dry ice). Most liquids under increased pressure freeze at higher temperatures because the pressure helps to hold the molecules together. However, the strong hydrogen bonds in water make it different: for some pressures higher than 1 atm (0.10 MPa), water freezes at a temperature below 0 °C (32 °F). Ice, water, and water vapour can coexist at

1764-574: A thin surface layer, which makes it particularly hazardous to walk across it. Another dangerous form of rotten ice to traverse on foot is candle ice, which develops in columns perpendicular to the surface of a lake. Because it lacks a firm horizontal structure, a person who has fallen through has nothing to hold onto to pull themselves out. Snow crystals form when tiny supercooled cloud droplets (about 10  μm in diameter) freeze . These droplets are able to remain liquid at temperatures lower than −18 °C (255 K; 0 °F), because to freeze,

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1848-442: Is a basic cause of freeze-thaw weathering of rock in nature and damage to building foundations and roadways from frost heaving . It is also a common cause of the flooding of houses when water pipes burst due to the pressure of expanding water when it freezes. Because ice is less dense than liquid water, it floats, and this prevents bottom-up freezing of the bodies of water. Instead, a sheltered environment for animal and plant life

1932-409: Is a function of the mass of the planet, the radius of the surface, and the amount and composition of the gases and their vertical distribution in the atmosphere. It is modified by the planetary rotation and local effects such as wind velocity, density variations due to temperature and variations in composition. The mean sea-level pressure (MSLP) is the atmospheric pressure at mean sea level . This

2016-427: Is abundant on the Earth's surface, particularly in the polar regions and above the snow line , where it can aggregate from snow to form glaciers and ice sheets . As snowflakes and hail , ice is a common form of precipitation , and it may also be deposited directly by water vapor as frost . The transition from ice to water is melting and from ice directly to water vapor is sublimation . These processes plays

2100-424: Is an important source of seasonal fresh water. The World Meteorological Organization defines several kinds of ice depending on origin, size, shape, influence and so on. Clathrate hydrates are forms of ice that contain gas molecules trapped within its crystal lattice. Ice that is found at sea may be in the form of drift ice floating in the water, fast ice fixed to a shoreline or anchor ice if attached to

2184-405: Is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so atmospheric pressure decreases with increasing elevation. Because the atmosphere is thin relative to the Earth's radius—especially the dense atmospheric layer at low altitudes—the Earth's gravitational acceleration as

2268-500: Is considered to be a mineral . Depending on the presence of impurities such as particles of soil or bubbles of air , it can appear transparent or a more or less opaque bluish-white color. Virtually all of the ice on Earth is of a hexagonal crystalline structure denoted as ice I h (spoken as "ice one h"). Depending on temperature and pressure, at least nineteen phases ( packing geometries ) can exist. The most common phase transition to ice I h occurs when liquid water

2352-498: Is cooled below 0  °C ( 273.15  K , 32  °F ) at standard atmospheric pressure . When water is cooled rapidly ( quenching ), up to three types of amorphous ice can form. Interstellar ice is overwhelmingly low-density amorphous ice (LDA), which likely makes LDA ice the most abundant type in the universe. When cooled slowly, correlated proton tunneling occurs below −253.15  °C ( 20  K , −423.67  °F ) giving rise to macroscopic quantum phenomena . Ice

2436-494: Is divided into four categories: pore ice, vein ice (also known as ice wedges), buried surface ice and intrasedimental ice (from the freezing of underground waters). One example of ice formation in permafrost areas is aufeis - layered ice that forms in Arctic and subarctic stream valleys. Ice, frozen in the stream bed, blocks normal groundwater discharge, and causes the local water table to rise, resulting in water discharge on top of

2520-435: Is equivalent to a volumetric expansion of 9%. The density of ice is 0.9167 –0.9168  g/cm at 0 °C and standard atmospheric pressure (101,325 Pa), whereas water has a density of 0.9998 –0.999863  g/cm at the same temperature and pressure. Liquid water is densest, essentially 1.00 g/cm , at 4 °C and begins to lose its density as the water molecules begin to form the hexagonal crystals of ice as

2604-484: Is extremely rare otherwise. Even icy moons like Ganymede are expected to mainly consist of other crystalline forms of ice. Water in the interstellar medium is dominated by amorphous ice, making it likely the most common form of water in the universe. Low-density ASW (LDA), also known as hyperquenched glassy water, may be responsible for noctilucent clouds on Earth and is usually formed by deposition of water vapor in cold or vacuum conditions. High-density ASW (HDA)

Ice (disambiguation) - Misplaced Pages Continue

2688-484: Is formed beneath the floating ice, which protects the underside from short-term weather extremes such as wind chill . Sufficiently thin floating ice allows light to pass through, supporting the photosynthesis of bacterial and algal colonies. When sea water freezes, the ice is riddled with brine-filled channels which sustain sympagic organisms such as bacteria, algae, copepods and annelids . In turn, they provide food for animals such as krill and specialized fish like

2772-452: Is formed by compression of ordinary ice I h or LDA at GPa pressures. Very-high-density ASW (VHDA) is HDA slightly warmed to 160 K under 1–2 GPa pressures. Ice from a theorized superionic water may possess two crystalline structures. At pressures in excess of 500,000 bars (7,300,000 psi) such superionic ice would take on a body-centered cubic structure. However, at pressures in excess of 1,000,000 bars (15,000,000 psi)

2856-511: Is instead reported in kilopascals. In the US weather code remarks, three digits are all that are transmitted; decimal points and the one or two most significant digits are omitted: 1,013.2 hPa (14.695 psi) is transmitted as 132; 1,000 hPa (100 kPa) is transmitted as 000; 998.7   hPa is transmitted as 987; etc. The highest sea-level pressure on Earth occurs in Siberia , where

2940-448: Is maximized 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 freezing level is below the altitude of 11,000 feet (3,400 m). Entrainment of dry air into strong thunderstorms over continents can increase

3024-464: Is over 70% ice on its surface is said to be covered by pack ice. Fully formed sea ice can be forced together by currents and winds to form pressure ridges up to 12 metres (39 ft) tall. On the other hand, active wave activity can reduce sea ice to small, regularly shaped pieces, known as pancake ice . Sometimes, wind and wave activity "polishes" sea ice to perfectly spherical pieces known as ice eggs . The largest ice formations on Earth are

3108-409: Is shifted toward slightly lower energies. Thus, ice appears blue, with a slightly greener tint than liquid water. Since absorption is cumulative, the color effect intensifies with increasing thickness or if internal reflections cause the light to take a longer path through the ice. Other colors can appear in the presence of light absorbing impurities, where the impurity is dictating the color rather than

3192-490: Is the atmospheric pressure normally given in weather reports on radio, television, and newspapers or on the Internet . The altimeter setting in aviation is an atmospheric pressure adjustment. Average sea-level pressure is 1,013.25 hPa (29.921 inHg; 760.00 mmHg). In aviation weather reports ( METAR ), QNH is transmitted around the world in hectopascals or millibars (1 hectopascal = 1 millibar), except in

3276-531: Is therefore slower than melting. Ice has long been valued as a means of cooling. In 400 BC Iran, Persian engineers had already developed techniques for ice storage in the desert through the summer months. During the winter, ice was transported from harvesting pools and nearby mountains in large quantities to be stored in specially designed, naturally cooled refrigerators , called yakhchal (meaning ice storage ). Yakhchals were large underground spaces (up to 5000 m ) that had thick walls (at least two meters at

3360-472: The Siberian High often attains a sea-level pressure above 1,050 hPa (15.2 psi; 31 inHg), with record highs close to 1,085 hPa (15.74 psi; 32.0 inHg). The lowest measurable sea-level pressure is found at the centres of tropical cyclones and tornadoes , with a record low of 870 hPa (12.6 psi; 26 inHg). Surface pressure is the atmospheric pressure at

3444-523: The United States , Canada , and Japan where it is reported in inches of mercury (to two decimal places). The United States and Canada also report sea-level pressure SLP, which is adjusted to sea level by a different method, in the remarks section, not in the internationally transmitted part of the code, in hectopascals or millibars. However, in Canada's public weather reports, sea level pressure

Ice (disambiguation) - Misplaced Pages Continue

3528-446: The bald notothen , fed upon in turn by larger animals such as emperor penguins and minke whales . When ice melts, it absorbs as much energy as it would take to heat an equivalent mass of water by 80 °C (176 °F). During the melting process, the temperature remains constant at 0 °C (32 °F). While melting, any energy added breaks the hydrogen bonds between ice (water) molecules. Energy becomes available to increase

3612-755: The triple point , which is exactly 273.16 K (0.01 °C) at a pressure of 611.657  Pa . The kelvin was defined as ⁠ 1 / 273.16 ⁠ of the difference between this triple point and absolute zero , though this definition changed in May 2019. 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 . Subjected to higher pressures and varying temperatures, ice can form in nineteen separate known crystalline phases at various densities, along with hypothetical proposed phases of ice that have not been observed. With care, at least fifteen of these phases (one of

3696-1339: The troposphere , the following equation (the barometric formula ) relates atmospheric pressure p to altitude h : p = p 0 ⋅ ( 1 − L ⋅ h T 0 ) g ⋅ M R 0 ⋅ L = p 0 ⋅ ( 1 − g ⋅ h c p ⋅ T 0 ) c p ⋅ M R 0 ≈ p 0 ⋅ exp ⁡ ( − g ⋅ h ⋅ M T 0 ⋅ R 0 ) {\displaystyle {\begin{aligned}p&=p_{0}\cdot \left(1-{\frac {L\cdot h}{T_{0}}}\right)^{\frac {g\cdot M}{R_{0}\cdot L}}\\&=p_{0}\cdot \left(1-{\frac {g\cdot h}{c_{\text{p}}\cdot T_{0}}}\right)^{\frac {c_{\text{p}}\cdot M}{R_{0}}}\approx p_{0}\cdot \exp \left(-{\frac {g\cdot h\cdot M}{T_{0}\cdot R_{0}}}\right)\end{aligned}}} The values in these equations are: Atmospheric pressure varies widely on Earth, and these changes are important in studying weather and climate . Atmospheric pressure shows

3780-416: The vapour pressure is equal to the atmospheric pressure around the liquid. Because of this, the boiling point of liquids is lower at lower pressure and higher at higher pressure. Cooking at high elevations, therefore, requires adjustments to recipes or pressure cooking . A rough approximation of elevation can be obtained by measuring the temperature at which water boils; in the mid-19th century, this method

3864-473: The "Ice King", worked on developing better insulation products for long distance shipments of ice, especially to the tropics; this became known as the ice trade. Between 1812 and 1822, under Lloyd Hesketh Bamford Hesketh 's instruction, Gwrych Castle was built with 18 large towers, one of those towers is called the 'Ice Tower'. Its sole purpose was to store Ice. Trieste sent ice to Egypt , Corfu , and Zante ; Switzerland, to France; and Germany sometimes

3948-400: The US is rated for a maximum of 1 ⁄ 2  psi (3.4 kPa; 34 mbar), which is approximately 14 w.g. Similar metric units with a wide variety of names and notation based on millimetres , centimetres or metres are now less commonly used. Pure water boils at 100 °C (212 °F) at earth's standard atmospheric pressure. The boiling point is the temperature at which

4032-656: The United States, with a combined value of shipments of $ 595,487,000. Home refrigerators can also make ice with a built in icemaker , which will typically make ice cubes or crushed ice. The first such device was presented in 1965 by Frigidaire . Ice forming on roads is a common winter hazard, and black ice particularly dangerous because it is very difficult to see. It is both very transparent, and often forms specifically in shaded (and therefore cooler and darker) areas, i.e. beneath overpasses . Atmospheric pressure In most circumstances, atmospheric pressure

4116-475: The ablation of ice. For example, the temperature of the Arctic Ocean is generally below the melting point of ablating sea ice. The phase transition from solid to liquid is achieved by mixing salt and water molecules, similar to the dissolution of sugar in water, even though the water temperature is far below the melting point of the sugar. However, the dissolution rate is limited by salt concentration and

4200-503: The atmospheric pressure at a given altitude. Temperature and humidity also affect the atmospheric pressure. Pressure is proportional to temperature and inversely related to humidity, and both of these are necessary to compute an accurate figure. The graph on the right above was developed for a temperature of 15 °C and a relative humidity of 0%. At low altitudes above sea level, the pressure decreases by about 1.2 kPa (12 hPa) for every 100 metres. For higher altitudes within

4284-419: The base) made of a specific type of mortar called sarooj made from sand, clay, egg whites, lime, goat hair, and ash. The mortar was resistant to heat transfer, helping to keep the ice cool enough not to melt; it was also impenetrable by water. Yakhchals often included a qanat and a system of windcatchers that could lower internal temperatures to frigid levels, even during the heat of the summer. One use for

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4368-427: 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, although to what extent is unclear. Artificial nuclei are used in cloud seeding . The droplet then grows by condensation of water vapor onto

4452-505: The extrapolation of pressure to sea level for locations above or below sea level. The average pressure at mean sea level ( MSL ) in the International Standard Atmosphere ( ISA ) is 1,013.25 hPa, or 1 atmosphere (atm), or 29.92 inches of mercury. Pressure (P), mass (m), and acceleration due to gravity (g) are related by P = F/A = (m*g)/A, where A is the surface area. Atmospheric pressure is thus proportional to

4536-449: 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. The density of ice increases slightly with decreasing temperature and has a value of 0.9340 g/cm at −180 °C (93 K). When water freezes, it increases in volume (about 9% for fresh water). The effect of expansion during freezing can be dramatic, and ice expansion

4620-465: The frequency of hail by promoting evaporative cooling which lowers the freezing 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. Ice pellets ( METAR code PL ) are

4704-534: The frozen layer. This water then freezes, causing the water table to rise further and repeat the cycle. The result is a stratified ice deposit, often several meters thick. Snow line and snow fields are two related concepts, in that snow fields accumulate on top of and ablate away to the equilibrium point (the snow line) in an ice deposit. Ice which forms on moving water tends to be less uniform and stable than ice which forms on calm water. Ice jams (sometimes called "ice dams"), when broken chunks of ice pile up, are

4788-636: The greatest ice hazard on rivers. Ice jams can cause flooding, damage structures in or near the river, and damage vessels on the river. Ice jams can cause some hydropower industrial facilities to completely shut down. An ice dam is a blockage from the movement of a glacier which may produce a proglacial lake . Heavy ice flows in rivers can also damage vessels and require the use of an icebreaker vessel to keep navigation possible. Ice discs are circular formations of ice floating on river water. They form within eddy currents , and their position results in asymmetric melting, which makes them continuously rotate at

4872-503: The hailstones to the upper part of the cloud. The updraft dissipates and the hailstones fall down, back into the updraft, and are lifted up again. Hail has a diameter of 5 millimetres (0.20 in) or more. Within 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. Stones of 19 millimetres (0.75 in), 25 millimetres (1.0 in) and 44 millimetres (1.75 in) are

4956-464: The ice exerted by any object. However, the significance of this hypothesis is disputed by experiments showing a high coefficient of friction for ice using atomic force microscopy . Thus, the mechanism controlling the frictional properties of ice is still an active area of scientific study. A comprehensive theory of ice friction must take into account all of the aforementioned mechanisms to estimate friction coefficient of ice against various materials as

5040-429: The ice itself. For instance, icebergs containing impurities (e.g., sediments, algae, air bubbles) can appear brown, grey or green. Because ice in natural environments is usually close to its melting temperature, its hardness shows pronounced temperature variations. At its melting point, ice has a Mohs hardness of 2 or less, but the hardness increases to about 4 at a temperature of −44 °C (−47 °F) and to 6 at

5124-456: The ice layer is caused by friction. However, this theory does not sufficiently explain why ice is slippery when standing still even at below-zero temperatures. Subsequent research suggested that ice molecules at the interface cannot properly bond with the molecules of the mass of ice beneath (and thus are free to move like molecules of liquid water). These molecules remain in a semi-liquid state, providing lubrication regardless of pressure against

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5208-471: The ice surfaces. Ice storm is a type of winter storm characterized by freezing rain , which produces a glaze of ice on surfaces, including roads and power lines . In the United States, a quarter of winter weather events produce glaze ice, and utilities need to be prepared to minimize damages. Hail forms in storm clouds when supercooled water droplets freeze on contact with condensation nuclei , such as dust or dirt . The storm's updraft blows

5292-481: The ice was to create chilled treats for royalty. There were thriving industries in 16th–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

5376-416: The ice which often settles when loaded with snow. An ice shove occurs when ice movement, caused by ice expansion and/or wind action, occurs to the extent that ice pushes onto the shores of lakes, often displacing sediment that makes up the shoreline. Shelf ice is formed when floating pieces of ice are driven by the wind piling up on the windward shore. This kind of ice may contain large air pockets under

5460-603: The ice, would melt a thin layer, providing sufficient lubrication for the blade to glide across the ice. Yet, 1939 research by Frank P. Bowden and T. P. Hughes found that skaters would experience a lot more friction than they actually do if it were the only explanation. Further, the optimum temperature for figure skating is −5.5 °C (22 °F; 268 K) and −9 °C (16 °F; 264 K) for hockey; yet, according to pressure melting theory, skating below −4 °C (25 °F; 269 K) would be outright impossible. Instead, Bowden and Hughes argued that heating and melting of

5544-427: The invention of refrigeration technology, the only way to safely store food without modifying it through preservatives was to use ice. Sufficiently solid surface ice makes waterways accessible to land transport during winter, and dedicated ice roads may be maintained. Ice also plays a major role in winter sports . Ice possesses a regular crystalline structure based on the molecule of water, which consists of

5628-515: The known exceptions being ice X) can be recovered at ambient pressure and low temperature in metastable form. The types are differentiated by their crystalline structure, proton ordering, and density. There are also two metastable phases of ice under pressure, both fully hydrogen-disordered; these are Ice IV and Ice XII. Ice XII was discovered in 1996. In 2006, Ice XIII and Ice XIV were discovered. Ices XI, XIII, and XIV are hydrogen-ordered forms of ices I h , V, and XII respectively. In 2009, ice XV

5712-495: The large number of glaciers it contains. They cover an area of around 80,000 km (31,000 sq mi), and have a combined volume of between 3,000-4,700 km . These glaciers are nicknamed "Asian water towers", because their meltwater run-off feeds into rivers which provide water for an estimated two billion people. Permafrost refers to soil or underwater sediment which continuously remains below 0 °C (32 °F) for two years or more. The ice within permafrost

5796-524: The most frequently reported hail sizes in North America. Hailstones can grow to 15 centimetres (6 in) and weigh more than 0.5 kilograms (1.1 lb). In large hailstones, latent heat released by further freezing may melt the outer shell of the hailstone. The hailstone then may undergo 'wet growth', where the liquid outer shell collects other smaller hailstones. The hailstone gains an ice layer and grows increasingly larger with each ascent. Once

5880-514: The process to an even older author, Ibn Bakhtawayhi, of whom nothing is known. 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. Most commercial icemakers produce three basic types of fragmentary ice: flake, tubular and plate, using a variety of techniques. Large batch ice makers can produce up to 75 tons of ice per day. In 2002, there were 426 commercial ice-making companies in

5964-425: The seafloor. Ice which calves (breaks off) from an ice shelf or a coastal glacier may become an iceberg. The aftermath of calving events produces a loose mixture of snow and ice known as Ice mélange . Sea ice forms in several stages. At first, small, millimeter-scale crystals accumulate on the water surface in what is known as frazil ice . As they become somewhat larger and more consistent in shape and cover,

6048-440: The structure may shift to a more stable face-centered cubic lattice. It is speculated that superionic ice could compose the interior of ice giants such as Uranus and Neptune. Ice is " slippery " because it has a low coefficient of friction. This subject was first scientifically investigated in the 19th century. The preferred explanation at the time was " pressure melting " -i.e. the blade of an ice skate, upon exerting pressure on

6132-705: The summer. The advent of artificial refrigeration technology made the delivery of ice obsolete. Ice is still harvested for ice and snow sculpture events . For example, a swing saw is used to get ice for the Harbin International Ice and Snow Sculpture Festival each year from the frozen surface of the Songhua River . The earliest known written process to artificially make ice is by the 13th-century writings of Arab historian Ibn Abu Usaybia in his book Kitab Uyun al-anba fi tabaqat-al-atibba concerning medicine in which Ibn Abu Usaybia attributes

6216-443: The surface of un-insulated windows. Hoar frost is common in the environment, particularly in the low-lying areas such as valleys . In Antarctica, the temperatures can be so low that electrostatic attraction is increased to the point hoarfrost on snow sticks together when blown by wind into tumbleweed -like balls known as yukimarimo . Sometimes, drops of water crystallize on cold objects as rime instead of glaze. Soft rime has

6300-441: The thermal energy (temperature) 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 . 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) bond stretch. Compared with water, this absorption

6384-486: The two ice sheets which almost completely cover the world's largest island, Greenland , and the continent of Antarctica . These ice sheets have an average thickness of over 1 km (0.6 mi) and have existed for millions of years. Other major ice formations on land include ice caps , ice fields , ice streams and glaciers . In particular, the Hindu Kush region is known as the Earth's "Third Pole" due to

6468-433: The water surface begins to look "oily" from above, so this stage is called grease ice . Then, ice continues to clump together, and solidify into flat cohesive pieces known as ice floes . Ice floes are the basic building blocks of sea ice cover, and their horizontal size (defined as half of their diameter ) varies dramatically, with the smallest measured in centimeters and the largest in hundreds of kilometers. An area which

6552-483: The weight per unit area of the atmospheric mass above that location. Pressure on Earth varies with the altitude of the surface, so air pressure on mountains is usually lower than air pressure at sea level. Pressure varies smoothly from the Earth's surface to the top of the mesosphere . Although the pressure changes with the weather, NASA has averaged the conditions for all parts of the earth year-round. As altitude increases, atmospheric pressure decreases. One can calculate

6636-567: Was 1,084.8 hPa (32.03 inHg) measured in Tosontsengel, Mongolia on 19 December 2001. The highest adjusted-to-sea level barometric pressure ever recorded (below 750 meters) was at Agata in Evenk Autonomous Okrug , Russia (66°53'   N, 93°28'   E, elevation: 261 m, 856 ft) on 31 December 1968 of 1,083.8 hPa (32.005 inHg). The discrimination is due to the problematic assumptions (assuming

6720-439: Was 870 hPa (0.858 atm; 25.69 inHg), set on 12 October 1979, during Typhoon Tip in the western Pacific Ocean. The measurement was based on an instrumental observation made from a reconnaissance aircraft. One atmosphere (101.325 kPa or 14.7 psi) is also the pressure caused by the weight of a column of freshwater of approximately 10.3 m (33.8 ft). Thus, a diver 10.3 m under water experiences

6804-456: Was allegedly copied by an Englishman who had seen the same activity in China. Ice was imported into England from Norway on a considerable scale as early as 1823. In the United States, the first cargo of ice was sent from New York City to Charleston, South Carolina , in 1799, and by the first half of the 19th century, ice harvesting had become a big business. Frederic Tudor , who became known as

6888-411: Was found at extremely high pressures and −143 °C. At even higher pressures, ice is predicted to become a metal ; this has been variously estimated to occur at 1.55 TPa or 5.62 TPa. As well as crystalline forms, solid water can exist in amorphous states as amorphous solid water (ASW) of varying densities. In outer space, hexagonal crystalline ice is present in the ice volcanoes , but

6972-509: Was supplied from Bavarian lakes. From 1930s and up until 1994, the Hungarian Parliament building used ice harvested in the winter from Lake Balaton for air conditioning. Ice houses were used to store ice formed in the winter, to make ice available all year long, and an early type of refrigerator known as an icebox was cooled using a block of ice placed inside it. Many cities had a regular ice delivery service during

7056-444: Was used by explorers. Conversely, if one wishes to evaporate a liquid at a lower temperature, for example in distillation , the atmospheric pressure may be lowered by using a vacuum pump , as in a rotary evaporator . An important application of the knowledge that atmospheric pressure varies directly with altitude was in determining the height of hills and mountains, thanks to reliable pressure measurement devices. In 1774, Maskelyne

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