Supercooling is the process of chilling a liquid below its freezing point, without it becoming solid. Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of The melting point of a solid is the temperature range at which it changes state from solid to Liquid. A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume.

A liquid below its freezing point will crystallize in the presence of a seed crystal or nucleus around which a crystal structure can form. Crystallization is the (natural or artificial process of formation of solid Crystals precipitating from a homogeneous --> identical Solution Nucleation is the onset of a Phase transition in a small region In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating However, lacking any such nucleus, the liquid phase can be maintained all the way down to the temperature at which crystal homogeneous nucleation occurs. In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties The homogeneous nucleation can occur above the glass transition where the system is an amorphous—that is, non-crystalline—solid. The glass transition temperature, T g is the temperature at which an Amorphous solid, such as Glass or a Polymer, becomes brittle

Water has a freezing point of 273. 15 K (0 °C or 32 °F) but can be supercooled at standard pressure down to its crystal homogeneous nucleation at almost 231 K (−42 °C). Nucleation is the onset of a Phase transition in a small region ^[1] If cooled at a rate on the order of 10⁶ K/s, the crystal nucleation can be avoided and water becomes a glass. Glass in the common sense refers to a Hard, Brittle, transparent Solid, such as that used for Windows many Its glass transition temperature is much colder and harder to determine, but studies estimate it at about 165 K (−108 °C). ^[2] Glassy water can be heated up to approximately 150 K (−123 °C). ^[1] In the range of temperatures between 231 K (−42 °C) and 150 K (−123 °C) experiments find only crystal ice.

Droplets of supercooled water often exist in stratiform and cumulus clouds. Stratus means layer or blanket in Latin A Stratus cloud (St is a Cloud belonging to a class characterized by horizontal layering with a uniform base A cumulus cloud' is a type of Cloud with noticeable vertical development and clearly defined edges A cloud is a visible mass of droplets or frozen crystals floating in the atmosphere above the surface of the Earth or another Planetary body They form into ice when they are struck by the wings of passing airplanes and abruptly crystallize. Ice is a Solid phase, usually crystalline, of a Non-metalic substance that is liquid or gas at Room temperature, such as Ammonia Overview Fixed-wing aircraft range from small training and recreational aircraft to Wide-body aircraft and military cargo aircraft. (This causes problems with lift, so aircraft that are expected to fly in such conditions are equipped with a deicing system. De-icing is the process of removing Ice from a Surface. Anti-icing is the process of Preventing ice from forming on a surface ) Freezing rain is also caused by supercooled droplets. Freezing rain is a type of precipitation that begins as Snow at higher altitude falling from a Cloud towards earth melts completely on its way down while passing

The process opposite to supercooling, the melting of a solid above the freezing point, is much more difficult, and a solid will almost always melt at the same temperature for a given pressure. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface It is, however, possible to superheat a liquid above its boiling point without it becoming gaseous. See Superheater for the device used in Steam engines In Physics, superheating (sometimes referred to as boiling retardation The boiling point of a liquid is the temperature at which the Vapor pressure of the liquid equals the environmental pressure surrounding the liquid

Constitutional supercooling

Constitutional supercooling occurs during solidification, is due to compositional changes, and results in cooling a liquid below the freezing point ahead of the solid-liquid interface. When solidifying a liquid, the interface is often unstable, and the velocity of the solid-liquid interface must be small in order to avoid constitutional supercooling.

Supercooled zones are observed when the liquidus temperature gradient at the interface is larger than the temperature gradient.

or

The slope of the liquidus phase boundary on the phase diagram is

The concentration gradient is related to points, C^LS and C^SL, on the phase diagram:

The minimum thermal gradient necessary to create a stable solid front is as expressed below.

See also

• Diamond dust, an Antarctic optical phenomenon
• Flash freezing
• Nucleation
• Supersaturation
• Vitrification

References

External links

• Supercooled Water Matt Sparks's blog entry about his experience with a cold garage and supercooling. Includes videos of supercooled water freezing after being agitated.
• Video example
• Video example #2