Hair ice

Hair ice on dead wood in Canada

"Ice wool" on dead wood

Hair ice , sometimes also called ice wool , consists of fine ice needles that can form on rotten and damp dead wood under suitable conditions . Unlike hydrometeors ( e.g. hoarfrost crystals ), hair ice is created from the water contained in the wood , not from humidity .

Similar-looking and often not distinct groups phenomena are Bandeis (Engl. Ice ribbons, ice flowers ) on plant stems and needle ice (Engl. Needle ice ) on the ground, both of which are formed, however, different.

Emergence

Scientifically, the formation of the hair ice, which is rarely observed, has not yet been researched very much. In 1918, the meteorologist Alfred Wegener described hair ice on wet dead wood. He suspected a “mold-like fungus ” as the trigger, but this was doubted by other scientists who assumed purely physical processes, such as those in the formation of Kammeis, as the cause.

A biophysical study by Gerhart Wagner and Christian Mätzler in 2008 largely confirmed Wegener's assumption. According to this, hair ice is triggered by the mycelium of winter-active fungi (including tube and stand mushrooms ), whose aerobic metabolism ( dissimilation ) produces gases that displace the slightly supercooled water in the wood to the surface. There it freezes and is pushed on by liquid that is forced in and that also freezes when it exits the wood. This only happens at temperatures just below freezing point , when the water in the wood has not yet frozen, but it does freeze in the slightly colder ambient air. A boundary condition for hair ice formation is also high humidity : If the air is not saturated with water vapor, the fine ice crystals sublime on the wood surface shortly after they have formed, so that long hair ice crystals cannot develop. A reproduction of hair ice is possible in experiments as long as the fungal mycelium in the wooden body is not killed.

literature

• Gerhart Wagner, Christian Mätzler: Hair ice - a rare biophysical phenomenon in winter. In: Naturwissenschaftliche Rundschau. Vol. 62, No. 3, ISSN  0028-1050 , 2009, pp. 117-123.
• James R. Carter: Flowers and Ribbons of Ice. In: Spectrum of Science . No. 1/2014, pp. 36–45 ( beginning of article freely available)
• D. Hofmann, G. Preuss, C. Mätzler: Evidence for biological shaping of hair ice . Biogeosciences Discussion , 12, 2015, 5293–5332, doi : 10.5194 / bgd-12-5293-2015

Web links

Commons : Haaris  - Collection of images, videos and audio files

• Many examples of hair ice, including those on stones, garden fences, etc. v. a. m. to grow
• Mysterious hair ice , SRF report with Christian Mätzler, 4:49 min

Individual evidence

1. ↑ Michael Streckfuß: Cotton candy in the forest. LWF, www.waldwissen.net. 2006.
2. ↑ Gerhart Wagner: Hair ice and ice cream. Two rare winter natural phenomena with unanswered questions. (PDF; 141 kB) The Alps, 11/2007. Pp. 64-67
3. ↑ Alfred Wegener : Hair ice on rotten wood. Die Naturwissenschaften 6/1, 1918. pp. 598–601.
4. ↑ Gerhart Wagner: Hair ice - a rare winter natural phenomenon. What do mushrooms have to do with it? (PDF; 111 kB) SZP / BSM 2005, pp. 268–271.
5. ↑ ^{a b c d e} Gerhart Wagner, Christian Mätzler: Hair ice on rotten hardwood as a biophysical phenomenon. ( Memento of the original from March 4, 2016 in the Internet Archive ) Info: The  archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Research Report No. 2008-05-MW. Institute for Applied Physics. University of Bern. September 6, 2008. pp. 1-31. (Hair Ice on Rotten Wood of Broadleaf Trees - a Biophysical Phenomenon, abstract and parts in English) ( PDF download ( Memento of the original from March 4, 2016 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this note. )