Seidenhaarige Eiskristalle im Bergischen Land, Naafbachtal

Hair ice, also known as ice wool or frost beard, is a type of

ice Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaq ...

that forms on dead wood and takes the shape of fine, silky hair. It is somewhat uncommon, and has been reported mostly at

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...

s between 45 and 55 °N in

broadleaf forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...

s. The meteorologist (and discoverer of

continental drift Continental drift is the hypothesis that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed. The idea of continental drift has been subsumed into the science of pla ...

)

Alfred Wegener Alfred Lothar Wegener (; ; 1 November 1880 – November 1930) was a German climatologist, geologist, geophysicist, meteorologist, and polar researcher. During his lifetime he was primarily known for his achievements in meteorology and a ...

described hair ice on wet dead wood in 1918,

: ''Haareis auf morschem Holz.'' Die Naturwissenschaften 6/1, 1918. S. 598–601. assuming some specific

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

as the catalyst, a theory mostly confirmed by Gerhart Wagner and Christian Mätzler in 2005.Gerhart Wagner:
Haareis – eine seltene winterliche Naturerscheinung. Was haben Pilze damit zu tun?
' SZP/BSM 2005.Gerhart Wagner, Christian Mätzler:
Haareis auf morschem Laubholz als biophysikalisches Phänomen.
'' Forschungsbericht Nr. 2008-05-MW. Universität Bern. 2008.
PDF-Download
)Gerhart Wagner, Christian Mätzler: ''Haareis - Ein seltenes biophysikalisches Phänomen im Winter.'' Naturwissenschaftliche Rundschau 62(3), S. 117–123 (2009), ISSN 0028-1050 In 2015, the fungus '' Exidiopsis effusa'' was identified as key to the formation of hair ice.

Formation

IJshaar,_in_Austerlitz,_Utrecht_(Netherlands)

Hair ice forms on moist, rotting wood from

broadleaf tree A broad-leaved, broad-leaf, or broadleaf tree is any tree within the diverse botanical group of angiosperms that has flat leaves and produces seeds inside of fruits. It is one of two general types of trees, the other being a conifer, a tree with n ...

s when temperatures are slightly under and the air is

humid Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depen ...

. The hairs appear to root at the mouth of wood rays (never on the bark), and their thickness is similar to the diameter of the wood ray channels. A piece of wood that produces hair ice once may continue to produce it over several years. Each of the smooth, silky hairs has a diameter of about and a length of up to . The hairs are brittle, but take the shape of curls and waves. They can maintain their shape for hours and sometimes days. This long lifetime indicates that something is preventing the small

ice crystal Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust. Formation The hugely symmetric shapes are due to depositional growth, na ...

s from recrystallizing into larger ones, since recrystallization normally occurs very quickly at temperatures near . In the year 2015, German and Swiss scientists identified the fungus '' Exidiopsis effusa'' as key to the formation of hair ice. The fungus was found on every hair ice sample examined by the researchers, and disabling the fungus with

fungicide Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

or hot water prevented hair ice formation. The fungus shapes the ice into fine hairs through an uncertain mechanism and likely stabilizes it by providing a recrystallization inhibitor similar to

antifreeze protein Antifreeze proteins (AFPs) or ice structuring proteins refer to a class of polypeptides produced by certain animals, plants, fungi and bacteria that permit their survival in temperatures below the freezing point of water. AFPs bind to small i ...

References

External links

Hair ice photos for WDR 5 Leonardo feature (German)

Video footage of Hair Ice with narration
{{ice Frost and rime Hydrology Water ice Plant physiology https://www.livescience.com/hair-ice-ireland-fungus.html

Formation

See also

References

External links