Ice crystal

 ( Crystal ) 

Ice crystals are solid water (known as ice) in symmetrical shapes including hexagonal columns, hexagonal plates, and dendritic crystals. Ice crystals are responsible for various atmospheric optical displays and cirrus cloud.

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Formation  At ambient temperature and pressure, water molecules have a V shape. The two hydrogen atoms bond to the oxygen atom at a 105° angle. Ice crystals have a hexagonal crystal lattice, meaning the water molecules arrange themselves into layered Hexagon upon freezing.

Slower crystal growth from colder and drier atmospheres produces more hexagonal symmetry. Depending on environmental temperature and humidity, ice crystals can develop from the initial hexagonal prism into many symmetric shapes.

Guido Visconti (2025). 9783540674207, Springer. ISBN 9783540674207

Possible shapes for ice crystals are columns, Needle ice, plates and dendrites. Mixed patterns are also possible. The symmetric shapes are due to depositional Crystal growth, which is when ice forms directly from water vapor in the atmosphere. Small spaces in atmospheric Dust can also collect water, freeze, and form ice crystals. This is known as nucleation. Snowflake form when additional vapor freezes onto an existing ice crystal..]]

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Trigonal and cubic crystals

Supercooling water refers to water below its Melting point that is still liquid. Ice crystals formed from supercooled water have Stacking fault in their layered hexagons. This causes ice crystals to display trigonal or Ice Ic symmetry depending on the temperature. Trigonal or cubic crystals form in the upper atmosphere where supercooling occurs.

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Square crystals

Water can pass through Lamination sheets of Graphite oxide unlike smaller molecules such as helium. When squeezed between two layers of graphene, water forms square ice crystals at room temperature. Researchers believe high pressure and the van der Waals force, an Force present between all molecules, drives the formation. The material is a new crystalline phase of ice.

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Weather phenomena

Ice crystals create optical Phenomenon like diamond dust and halos in the sky due to light reflecting off of the crystals in a process called scattering.

Cirrus cloud and ice fog are made of ice crystals. Cirrus clouds are often the sign of an approaching warm front, where warm and moist air rises and freezes into ice crystals. Ice crystals rubbing against each other also produces lightning. The crystals normally fall horizontally, but Electric field can cause them to clump together and fall in other directions.

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Detection

ice crystals imaged with a scanning electron microscope. The false color.]]The aerospace industry is working to design a radar that can detect ice crystal environments to discern hazardous flight conditions. Ice crystals can melt when they touch the surface of warm aircraft, and refreeze due to environmental conditions. The accumulation of ice around the engine damages the aircraft. Weather forecasting uses differential reflectivity Weather radar to identify types of precipitation by comparing a droplet's horizontal and vertical lengths. Ice crystals are larger in the horizontal direction and are thus detectable.

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See also

• Snow
• Snowflake
• Ice spike
• Ice lens
• Icicle

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External links

• SnowCrystals.com!, at Caltech
• American Meteorological Society Glossary

Categories: Crystal, Clouds, Fog And Precipitation, Atmospheric Optical Phenomena

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