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Ice crystal

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A close-up of growing ice crystals displaying typical hexagonal symmetry.

Ice crystalsare solidiceinsymmetricalshapes includinghexagonalcolumns, hexagonal plates, anddendritic crystals.[1]Ice crystals are responsible for variousatmosphericopticdisplays andcloud formations.[1][2]

Formation[edit]

An example of a hexagonal plate (top) and a hexagonal column (bottom), typical ice crystal shapes.

At ambient temperature and pressure,water moleculeshave a V shape. The twohydrogenatoms bond to theoxygenatom at a 105° angle.[3]Ice crystals have a hexagonalcrystal lattice,meaning the water molecules arrange themselves into layeredhexagonsupon freezing.[1]

Slower crystal growth from colder and drier atmospheres produces more hexagonal symmetry.[2]Depending on environmentaltemperatureandhumidity,ice crystals can develop from the initial hexagonal prism into many symmetric shapes.[4]Possible shapes for ice crystals are columns,needles,plates anddendrites.Mixed patterns are also possible.[1]The symmetric shapes are due todepositionalgrowth,which is when ice forms directly from water vapor in the atmosphere.[5]Small spaces in atmosphericparticlescan also collect water, freeze, and form ice crystals.[6][7]This is known asnucleation.[8]Snowflakesform when additional vapor freezes onto an existing ice crystal.[9][10]

Further freezing of water on an ice crystal producessnowflakes.

Trigonal and cubic crystals[edit]

Supercooledwater refers to water below itsfreezing pointthat is still liquid.[11]Ice crystals formed from supercooled water havestacking defectsin their layered hexagons. This causes ice crystals to displaytrigonalorcubicsymmetry depending on the temperature. Trigonal or cubic crystals form in the upper atmosphere where supercooling occurs.[12][13]

Square crystals[edit]

Water can pass throughlaminatedsheets ofgraphene oxideunlike smaller molecules such ashelium.When squeezed between two layers ofgraphene,water forms square ice crystals at room temperature. Researchers believe high pressure and thevan der Waals force,anattractive forcepresent between all molecules, drives the formation. The material is a new crystalline phase of ice.[3][14]

Weather phenomena[edit]

Ahalocreated by light reflecting off of ice crystals in cirrus clouds. This specific halo is called a46° halo.

Ice crystals create opticalphenomenalikediamond dustandhalosin the sky due to light reflecting off of the crystals in a process calledscattering.[1][2][15]

Cirrus cloudsandice fogare made of ice crystals.[1][16]Cirrus clouds are often the sign of an approachingwarm front,where warm and moist air rises and freezes into ice crystals.[17][18]Ice crystals rubbing against each other also produceslightning.[19][20]The crystals normally fall horizontally,[21]butelectric fieldscan cause them to clump together and fall in other directions.[22][23]

Detection[edit]

Dendriticice crystals imaged with ascanning electron microscope.Thecolors are computer generated.

Theaerospace industryis 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.[24][25]Weather forecasting uses differential reflectivityweather radarsto identify types ofprecipitationby comparing a droplet's horizontal and vertical lengths.[26]Ice crystals are larger in the horizontal direction[15]and are thus detectable.

See also[edit]

References[edit]

  1. ^abcdef"ice crystal".Glossary of Meteorology.American Meteorological Society.Retrieved2023-03-29.
  2. ^abc"Ice Crystal Halos".www.its.caltech.edu.Retrieved2023-03-30.
  3. ^abPuiu, Tibi (2015-03-27)."Sandwiching water between graphene makes square ice crystals at room temperature".ZME Science.Retrieved2023-03-30.
  4. ^Visconti, Guido (2001).Fundamentals of physics and chemistry of the atmosphere.Berlin: Springer.ISBN3-540-67420-9.OCLC46320998.
  5. ^"Sublimation and deposition - Energy Education".energyeducation.ca.Retrieved2023-04-10.
  6. ^Utah, University of."We've been thinking of how ice forms in cirrus clouds all wrong".phys.org.Retrieved2023-03-30.
  7. ^"How ice crystals form in clouds".Wiley Analytical Science Magazine.Retrieved2023-03-29.
  8. ^UCL (2016-12-09)."Understanding how ice crystals form in clouds".UCL News.Retrieved2023-04-10.
  9. ^"Growth Rates and Habits of Ice Crystals between −20° and −70°C - Google Search".www.google.com.Retrieved2024-03-10.
  10. ^"How do snowflakes form? Get the science behind snow".www.noaa.gov.19 December 2016.Retrieved2023-03-30.
  11. ^"Supercool Clouds".earthobservatory.nasa.gov.2014-12-20.Retrieved2023-04-10.
  12. ^Murray, Benjamin J.; Salzmann, Christoph G.; Heymsfield, Andrew J.; Dobbie, Steven; Neely, Ryan R.; Cox, Christopher J. (2015-09-01)."Trigonal Ice Crystals in Earth's Atmosphere".Bulletin of the American Meteorological Society.96(9): 1519–1531.Bibcode:2015BAMS...96.1519M.doi:10.1175/BAMS-D-13-00128.1.ISSN0003-0007.S2CID120907603.
  13. ^"Cubic ice (ice Ic) structure".water.lsbu.ac.uk.Retrieved2023-04-10.
  14. ^Algara-Siller, G.; Lehtinen, O.; Wang, F. C.; Nair, R. R.; Kaiser, U.; Wu, H. A.; Geim, A. K.; Grigorieva, I. V. (2015)."Square ice in graphene nanocapillaries".Nature.519(7544): 443–445.arXiv:1412.7498.Bibcode:2015Natur.519..443A.doi:10.1038/nature14295.ISSN1476-4687.PMID25810206.S2CID4462633.
  15. ^abGedzelman, S. D. (2003-01-01),"OPTICS, ATMOSPHERIC | Optical Phenomena",in Holton, James R. (ed.),Encyclopedia of Atmospheric Sciences,Oxford: Academic Press, pp. 1583–1594,doi:10.1016/b0-12-227090-8/00284-0,ISBN978-0-12-227090-1,retrieved2023-03-30
  16. ^"Ice fog".Glossary of Meteorology.American Meteorological Society.Retrieved2023-03-29.
  17. ^"Cirrus Clouds | Center for Science Education".scied.ucar.edu.Retrieved2023-03-30.
  18. ^"Cirrus clouds".Met Office.Retrieved2023-03-30.
  19. ^Plait, Phil (2016-11-16)."Ice Crystals Above Clouds Dance to the Tune of Electricity".Slate.ISSN1091-2339.Retrieved2023-03-30.
  20. ^Canada, Environment and Climate Change (2011-04-15)."How lightning works".www.canada.ca.Retrieved2023-03-30.
  21. ^Stillwell, Robert A.; Neely, Ryan R.; Thayer, Jeffrey P.; Walden, Von P.; Shupe, Matthew D.; Miller, Nathaniel B. (2019-11-27)."Radiative Influence of Horizontally Oriented Ice Crystals over Summit, Greenland".Journal of Geophysical Research: Atmospheres.124(22): 12141–12156.Bibcode:2019JGRD..12412141S.doi:10.1029/2018JD028963.ISSN2169-897X.S2CID210640681.
  22. ^Libbrecht, Kenneth G."Electric Snow Crystal Growth".www.its.caltech.edu.Retrieved2023-03-30.
  23. ^Latham, J.; Saunders, C. P. R. (1964)."Aggregation of Ice Crystals in Strong Electric Fields".Nature.204(4965): 1293–1294.Bibcode:1964Natur.204.1293L.doi:10.1038/2041293a0.ISSN1476-4687.S2CID8747928.
  24. ^Heidman, Kelly (2015-08-11)."Flight Campaign Studies Radar Detection of Ice Crystal Icing".NASA.Retrieved2023-03-30.
  25. ^Lukas, Jan; Badin, Pavel (2019-06-10)."High Altitude Ice Crystal Detection with Aircraft X-band Weather Radar".SAE International Journal of Advances and Current Practices in Mobility.2(1): 256–264.doi:10.4271/2019-01-2026.ISSN2641-9637.S2CID182542723.
  26. ^US Department of Commerce, NOAA."Dual-Pol Products".www.weather.gov.Retrieved2023-03-30.

External links[edit]

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