Ice is water frozen into a solid state. 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.
In the Solar System, ice is abundant and occurs naturally from as
close to the Sun as Mercury to as far away as the
Oort cloud objects.
Beyond the Solar System, it occurs as interstellar ice. It is abundant
on Earth's surface – particularly in the polar regions and
above the snow line – and, as a common form of precipitation
and deposition, plays a key role in Earth's water cycle and climate.
It falls as snowflakes and hail or occurs as frost, icicles or ice
Ice molecules can exhibit seventeen or more different phases (packing
geometries) that depend on temperature and pressure. When water is
cooled rapidly (quenching), up to three different types of amorphous
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
Earth's surface and in its atmosphere is of a hexagonal crystalline
structure denoted as ice Ih (spoken as "ice one h") with minute traces
of cubic ice denoted as ice Ic. The most common phase transition to
ice Ih occurs when liquid water is cooled below 0°C (273.15K, 32°F)
at standard atmospheric pressure. It may also 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
Ice is used in a variety of ways, including cooling, winter sports and
1 Physical properties
1.2 Friction properties
2 Natural formation
2.1 On the oceans
2.2 On land and structures
2.3 On rivers and streams
2.4 On lakes
2.5 In the air
2.5.1 Rime ice
2.5.5 Diamond dust
4 Role in human activities
4.1.2 Mechanical production
4.2.2 Water-borne travel
4.2.3 Air travel
4.3 Recreation and sports
4.4 Other uses
5 "Ice" of other materials
6 See also
8 External links
The three-dimensional crystal structure of H2O ice Ih (c) is composed
of bases of H2O ice molecules (b) located on lattice points within the
two-dimensional hexagonal space lattice (a). 
As a naturally occurring crystalline inorganic solid with an ordered
structure, ice fits the properties of a mineral. It possesses a
regular crystalline structure based on the molecule of water, which
consists of 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
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, whereas water has a density
of 0.9998 g/cm3 at the same temperature. 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 (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 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
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 has been argued that without this property, natural
bodies of water would freeze, in some cases permanently, from the
bottom up, 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 while protecting the underside from short-term
weather extremes such as wind chill. This creates a sheltered
environment for 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, which in
turn provide food for animals such as krill and specialised fish like
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. During the melting process,
the temperature remains constant at 0 °C. While melting, any
energy added breaks the hydrogen bonds between ice (water) molecules.
Energy becomes available to increase 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 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
Other colors can appear in the presence of light absorbing impurities,
where the impurity is dictating the color rather than the ice itself.
For instance, icebergs containing impurities (e.g., sediments, algae,
air bubbles) can appear brown, grey or green.
Ice IV" redirects here. For the high speed train, see ICE 4.
Ice X" redirects here. For other uses, see Icex (other).
Pressure dependence of ice melting
Ice may be any one of the 17 known solid crystalline phases of water,
or in an amorphous solid state at various densities.
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, as shown in the phase diagram below. The
melting of ice under high pressures is thought to contribute to the
movement of glaciers.
Ice, water, and water vapour can coexist at the triple point, which is
exactly 273.16 K (0.01 °C) at a pressure of
611.657 Pa. The kelvin is in fact defined as 1/273.16 of
the difference between this triple point and absolute zero. Unlike
most other solids, ice is difficult to superheat. In an experiment,
ice at −3 °C was superheated to about 17 °C for about
Subjected to higher pressures and varying temperatures, ice can form
in 16 separate known phases. With care, all these phases except 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 IV and XII.
Ice XII was discovered in
1996. In 2006, XIII and XIV were discovered. Ices XI, XIII, and
XIV are hydrogen-ordered forms of ices Ih, V, and XII respectively. In
2009, ice XV 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 ice (ASW) of varying densities.
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) is
formed by compression of ordinary ice Ih or LDA at GPa pressures.
Very-high-density ASW (VHDA) is HDA slightly warmed to 160K under
1–2 GPa pressures.
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 by volcanic action.
Log-lin pressure-temperature phase diagram of water. The Roman
numerals correspond to some ice phases listed below.
An alternative formulation of the phase diagram for certain ices and
other phases of water
Amorphous ice is an ice lacking crystal structure.
exists in three forms: low-density (LDA) formed at atmospheric
pressure, or below, high density (HDA) and very high density amorphous
ice (VHDA), forming at higher pressures. LDA forms by extremely quick
cooling of liquid water ("hyperquenched glassy water", HGW), by
depositing water vapour on very cold substrates ("amorphous solid
water", ASW) or by heating high density forms of ice at ambient
Normal hexagonal crystalline ice. Virtually all ice in the biosphere
is ice Ih, with the exception only of a small amount of ice Ic.
A metastable cubic crystalline variant of ice. The oxygen atoms are
arranged in a diamond structure. It is produced at temperatures
between 130 and 220 K, and can exist up to 240 K, when it
transforms into ice Ih. It may occasionally be present in the upper
A rhombohedral crystalline form with highly ordered structure. Formed
from ice Ih by compressing it at temperature of 190–210 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. Denser
A metastable rhombohedral phase. It can be formed by heating
high-density amorphous ice slowly at a pressure of 810 MPa. It
doesn't form easily without a nucleating agent.
A monoclinic crystalline phase. Formed by cooling water to 253 K
at 500 MPa. Most complicated structure of all the phases.
A tetragonal crystalline phase. Formed by cooling water to 270 K
at 1.1 GPa. Exhibits Debye relaxation.
A cubic phase. The hydrogen atoms' positions are disordered. Exhibits
Debye relaxation. The hydrogen bonds form two interpenetrating
A more ordered version of ice VII, where the hydrogen atoms assume
fixed positions. It is formed from ice VII, by cooling it 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
between 200 MPa and 400 MPa. It has density of
1.16 g/cm3, slightly higher than ordinary ice.
Proton-ordered symmetric ice. Forms at about 70 GPa.
An orthorhombic, low-temperature equilibrium form of hexagonal ice. It
Ice XI is considered the most stable configuration
of ice Ih.
A tetragonal, metastable, dense crystalline phase. It is observed in
the phase space of ice V and ice VI. It can be prepared 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).
A monoclinic crystalline phase. Formed by cooling water to below
130 K at 500 MPa. The proton-ordered form of ice V.
An orthorhombic crystalline phase. Formed below 118 K at
1.2 GPa. The proton-ordered form of ice XII.
The proton-ordered form of ice VI formed by cooling water to around
80–108 K at 1.1 GPa.
The least dense crystalline form of water, topologically equivalent to
the empty structure of sII Clathrate hydrates.
Frozen waterfall in southeast New York
The low coefficient of friction ("slipperiness") of ice has been
attributed to the pressure of an object coming into contact with the
ice, melting a thin layer of the ice and allowing the object to glide
across the surface. For example, the blade of an ice skate, upon
exerting pressure on the ice, would melt a thin layer, providing
lubrication between the ice and the blade. This explanation, called
"pressure melting", originated in the 19th century. It, however, did
not account for skating on ice temperatures lower than
−4.0 °C, which is often skated upon.
A second theory describing the coefficient of friction of ice
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 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.
A third theory is "friction heating", which suggests that friction of
the material is the cause of the ice layer melting. However, this
theory does not sufficiently explain why ice is slippery when standing
still even at below-zero temperatures.
A comprehensive theory of ice friction takes into account all the
above-mentioned friction mechanisms. This model allows
quantitative estimation of the friction coefficient of ice against
various materials as a function of temperature and sliding speed. In
typical conditions related to winter sports and tires of a vehicle on
ice, melting of a thin ice layer due to the frictional heating is the
primary reason for the slipperiness.
Feather ice on the plateau near Alta, Norway. The crystals form at
temperatures below −30 °C (−22 °F).
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 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
On the oceans
Main article: Sea ice
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
the sea bottom.
Ice which calves (breaks off) from an ice shelf or
glacier may become an ice berg.
Sea ice can be forced together by
currents and winds to form pressure ridges up to 12 metres
(39 ft) tall. Navigation through areas of sea ice occurs in
openings called "polynyas" or "leads" or requires the use of a special
ship called an "icebreaker".
On land and structures
Ice on deciduous tree after freezing rain
Ice on land ranges from the largest type called an "ice sheet" to
smaller ice caps and ice fields to glaciers and ice streams to the
snow line and snow fields.
Aufeis is 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 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.
Freezing rain is a type of winter storm called an ice storm where rain
falls and then freezes producing a glaze of ice.
Ice can also form
icicles, similar to stalactites in appearance, or stalagmite-like
forms as water drips and re-freezes.
The term "ice dam" has three meanings (others discussed below). On
structures, an ice dam is the buildup of ice on a sloped roof which
stops melt water from draining properly and can cause damage from
water leaks in buildings.
On rivers and streams
A small frozen rivulet
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 the greatest ice hazard
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 to keep navigation possible.
Ice discs are circular formations of ice surrounded by water in a
Pancake ice is a formation of ice generally created in areas with less
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 the ice which often settles when loaded with snow.
Shelf ice occurs when floating pieces of ice are driven by the wind
piling up on the windward shore.
Candle ice is a form of rotten ice that develops in columns
perpendicular to the surface of a lake.
In the air
Ice formation on vehicle windshield
Rime is a type of ice formed on cold objects when drops of water
crystallize on them. This can be observed in foggy weather, when the
temperature drops during the night.
Soft rime contains a high
proportion of trapped air, making it appear white rather than
transparent, and giving it a density about one quarter of that of pure
Hard rime is comparatively dense.
An accumulation of ice pellets
Ice pellets are a form of precipitation consisting of small,
translucent balls of ice. This form of precipitation is also referred
to as "sleet" by the United States National Weather Service. (In
Commonwealth English "sleet" refers to a mixture of rain and snow).
Ice pellets are usually smaller than hailstones. They often bounce
when they hit the ground, and generally do not freeze into a solid
mass unless mixed with freezing rain. The
METAR code for ice pellets
Ice pellets form when a layer of above-freezing air is located between
1,500 and 3,000 metres (4,900 and 9,800 ft) above the ground,
with sub-freezing air both above and below it. This causes the partial
or complete melting of any snowflakes falling through the warm layer.
As they fall back into the sub-freezing layer closer to the surface,
they re-freeze into ice pellets. However, if the sub-freezing layer
beneath the warm layer is too small, the precipitation will not have
time to re-freeze, and freezing rain will be the result at the
surface. A temperature profile showing a warm layer above the ground
is most likely to be found in advance of a warm front during the cold
season, but can occasionally be found behind a passing cold front.
Main article: Hail
A large hailstone, about 6 cm (2.4 in) in diameter
Like other precipitation, 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 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 just
larger than golf ball-sized are one of the most frequently reported
hail sizes. 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 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
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 the frequency
of hail by promoting evaporational 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
Hail in the tropics occurs mainly at higher
Main article: Snowflake
Snowflakes by Wilson Bentley, 1902.
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, 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) 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 the ice surfaces.
Main article: Diamond dust
So-called "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. The
METAR identifier for diamond dust within
international hourly weather reports is IC.
Main article: Ablation
Ablation of ice refers to both its melting and its dissolution.
In fresh ambient melting describes a phase transition from solid to
liquid. To melt ice means breaking the 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 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 velocity 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 a velocity that depends as
(T∞ - 4 °C)4/3 on the water temperature, T∞, for
In salty ambient conditions, dissolution rather than melting often
causes the ablation of ice. E.g. 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.
Hence dissolution is rate limited by salt transport whereas melting
can occur at much higher rates that are characteristic for heat
Role in human activities
Humans have used ice for cooling and food preservation for centuries,
relying on harvesting natural ice in various forms and then
transitioning to the mechanical production of the material.
presents a challenge to transportation in various forms and an setting
for winter sports.
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 of a special mortar
called sarooj, composed of sand, clay, egg whites, lime, goat hair,
and ash 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.
Harvesting ice on
Lake St. Clair
Lake St. Clair in Michigan, c. 1905
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 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
Charleston, South Carolina
Charleston, South Carolina in 1799, and by the first half
of the 19th century, ice harvesting had become big business. Frederic
Tudor, who became known as the "
Ice King", worked on developing better
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; Switzerland sent it to
France; and Germany sometimes was supplied from Bavarian lakes.
Hungarian Parliament building used ice harvested in the winter
Lake Balaton for air conditioning.
Ice houses 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. For example,
a swing saw is used to get ice for the Harbin International
Snow Sculpture Festival each year from the frozen surface of the
Layout of a late 19th-Century ice factory
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 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. Stand-alone icemaker units that make ice cubes are
often called ice machines.
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Ice can present challenges to safe transportation on land, sea and in
Road ice decreases tire traction, thereby affecting driving safety.
Ice forming on roads is a dangerous winter hazard.
Black ice is very
difficult to see, because it lacks the expected frosty surface.
Whenever there is freezing 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
Ice scrapers are tools designed to break the ice free and
clear the windows, though removing the ice can be a long and laborious
Far enough below the freezing point, a thin layer of ice crystals can
form on the inside surface of 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 insulation.
When the outdoor temperature stays below freezing 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).
Channel through ice for ship traffic on
Lake Huron with ice breakers
For ships, ice presents two distinct hazards. Spray and freezing 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 being the Titanic. 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
Rime ice on the leading edge of an aircraft wing, partially released
by the black pneumatic boot.
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
across the Atlantic, the British aviators Captain John Alcock and
Arthur Whitten Brown
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
Vickers Vimy aircraft they were flying.
One vulnerability effected by icing that is 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. Thus, in humid
near-freezing 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
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 more easily than
previously believed. In most cases, the engines can be quickly
restarted and 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.
Recreation and sports
Skating fun by 17th century Dutch painter Hendrick Avercamp
Ice also plays a central role in winter recreation and in many sports
such as ice skating, tour skating, ice hockey, bandy, 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. Another sport
is 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 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).
Ice can be used to reduce swelling (by decreasing blood flow) and pain
by pressing it against an area of the body.
Ice pier during 1983 cargo operations. McMurdo Station, Antarctica
Engineers used the formidable strength of pack ice when they
constructed Antarctica's first floating ice pier in 1973. 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 frozen 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 or
by spraying water 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.
In cold climates, roads are regularly prepared on floating ice of
lakes and archipelago areas. Temporarily, even a railroad has been
built on ice.
During World War II,
Project Habbakuk was an Allied programme which
investigated the use of pykrete (wood fibers mixed with ice) as a
possible material for warships, especially aircraft carriers, due to
the ease with which a vessel immune to torpedoes, and a large deck,
could be constructed by ice. A small-scale prototype was built,
but the need for such a vessel in the war was removed prior to
building it in full-scale.
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.
Ice has even been used as the material for a variety of musical
instruments, for example by percussionist Terje Isungset.
Ice was once used to cool refrigerators in the 19th century, called
Ice can be used as part of an air conditioning system, using battery-
or solar-powered fans to blow hot air over the ice. This is especially
useful during heat waves when power is out and standard (electrically
powered) air conditioners do not work.
"Ice" of other materials
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 or around 100 K. The best known example is
dry ice, the solid form of carbon dioxide.
A "magnetic analogue" of ice is also realized 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
Density of ice versus water
Pumpable ice technology
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Look up ice in Wiktionary, the free dictionary.
Commons has media related to Ice.
Wikisource has the text of The New Student's Reference Work article
The National Snow and
Ice Data Center, based in the United States
The phase diagram of water, including the ice variants
Webmineral listing for Ice
MinDat.org listing and location data for Ice
The physics of ice
The phase diagrams of water with some high pressure diagrams
'Unfreezable' 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
Amazing ice at Lac Leman
The Surprisingly Cool History of Ice
the solid state of water
Circle or disc
Frost flower (sea ice)
Macroscopic quantum phenomena
Boating / yachting
Pollution / quality
Ambient standards (USA)
Clean Air Act (USA)
Fossil fuels (peak oil)
Non-timber forest products
Types / location
storage and recovery
Earth Overshoot Day
Renewable / Non-renewable
Agriculture and agronomy