Hair Ice  

Dr. James R. Carter, Professor Emeritus

Geography-Geology Department

Illinois State University, Normal IL 61790-4400


In the process of Ice Segregation cold water moves through a medium toward the presence of ice, freezes and adds to the ice.   This sometimes takes place in dead wood to produce Hair Ice / Haareis.  When Ice Segregation occurs at or near the surface of soil, it produces Needle Ice .  When it occurs on plant stems it produces Ice Flowers .  And, when it occurs on small rocks it is called Pebble Ice .  

In all cases these growths of ice occur at the Earths surface when moisture in the medium is liquid and the air temperature is below freezing.  Normally such conditions occur over night in late fall, winter and early spring.  As the water freezes latent heat of fusion is released helping keep everything from becoming even colder.  As long as there is a balance of energy flows keeping the water in the medium from freezing and keeping the surface of the medium below freezing ice can continue to grow on the medium to create a variety of ice formations. (Outcalt, 1971)  In all of these cases the resulting ice formations have some similarities but some distinct differences.

I was introduced to Hair Ice when I received an email from Geoff Gaynor in Wales asking about some ice in his photographs. He sent the inquiry to me because I had web pages showing Ice Flowers and this ice looked quite similar. Ice Flowers grow on plant stems but this ice was on pieces of wood on the ground. With his permission I posted his photos on my web site.

Figure 1 -- Two examples of what I now as Hair Ice from Geoff Gaynor in Wales.  This form of ice segregation occurs on dead wood.

Then I got my first set of photos of Hair Ice from someone in the Pacific Northwest of North America.  Such ice seems to be quite common in the State of Washington, USA, and British Columbia, Canada.  Over the years I have heard from many who have seen such ice in that area.

Figure 2 -- These two images come from bobbi fabellano of Washington.  She called this "silk frost," a name she heard from others, She proposed the name "cotton candy frost" which is quite appropriate in many ways.  Over time she has sent me many photos of Hair Ice.

While the term 'frost' is used frequently as part of such names, these ice formations are not a product of frost.  Frost forms when air cools forcing moisture to condense as deposits of ice on surfaces.  As such frost never forms as the fine threads we see here.   However it is not uncommon to find frost near the occurrence of Hair Ice because both occur with the decrease of temperatures from above freezing to below.  And, because ice must be present to initiate the Ice Segregation process it appears that frost crystals are required to start the process. 

The next collection of photos of Hair Ice were from Joaquim Mittendorf of Sweden who found his examples of Hair Ice in the Harz Mountains of Germany. 

Figure 3 -- Good example of Hair Ice on a piece of dead wood from Joaquim Mittendord.  Note that the ice formed only on the bare wood where there is no bark.  This is consistent with what others have reported.

Lawler (1988) publised a bibliography of Needle Ice listing 267 references dating back to 1824.  In this bibliography a few of the entries refer to Hair Ice and some of the first writings about Hair Ice were based on Haareis found in the Harz Mountains of Germany where Mittendorf took his photos. 

I have only seen Hair Ice / Haareis in photos and not in person because it does not occur in my part of North America.  Then in 2008 I heard from Dr. Gerhart Wagner of Switzerland who has been studying Haareis for decades and by that time had published two articles on Haareis.  (available for download   and )   At that time he had not seen Ice Flowers and so we shared experiences with what we knew and did not know. 

In 2008 Dr. Wagner and Dr. Christian Matzler published "Haareis auf morschem Laubholz als biophysikalisches Phanomen" Hair Ice on Rotten Wood of Broadleaf Trees - a biophysical phenomenon.  This is a 31 page paper with many photos and some material in English. 

Then in 2009 Drs. Wagner and Matzler published "Haareis - Ein seltenese biophysikalisches Phanomen im Winter" in Naturwissenschaftliche Rundschau, NR-729, pp. 117-123.

In 2012 Drs. Matzler, Wagner, Preuss and Hofmann produced "Enlightening the Mystery of Hair Ice ", a 38 page paper available in English as a pdf file from the University of Bern.  You must request a copy to be sent to you via email so they can determine who is interested in the subject.  This paper is a translation and expansion of the 2008 paper and Includes a reprint of the 1918 paper by Dr. Alfred Wegener "Haareis auf Morschem Holz" which was published in Die Naturwissenschaften. 

This 2012 paper is based on ice they observed in Switzerland or grew on wood gathered in Switzerland.  They conclude that the formation of Hair Ice is dependent on a fungus being present in the wood they tested.  They find the melt water from Hair Ice contains a significant amount of organic carbon.  Ice segregation is the driving force but the fungus must be there.  A supporting argument for the fungus is that as Hair Ice melts it decays into droplets on a web and the web is made up of material that could come from the fungus.  Hair Ice does not fall off the wood in whole as does the ice that forms on plant stems and pebbles. 

They make some interesting observations in their 2012 paper.  Because they had to determine if the source of the water was from a bio-chemical transformation or from accumulated water from precipitation, they employ the term 'basicryogen' to refer to the water that is from within the medium.  That is, water that entered the dead wood as water, be it from rain, snow or dew.  They refer to the holes from which the ice grows as wood rays.  Note that unlike Ice Flowers, Hair Ice does not emerge from cracks or lines in the wood but from holes.  They note that the diameter of a strand of Hair Ice might be 0.01 mm and that it may have a length of up to 10 cm, giving an exceptionally long length/diameter ratio.  (p. 33) 

Mention should be made of a YouTube site which is a 12 minute discussion by Dr. Wagner interspersed with four time-lapse videos showing the growth of ice on pieces of dead wood.  It is in German.

In 2015 Hoffman, Preuss and Matzler published Evidence for Biological Shaping of Hair Ice in Biogeosciences.  This has become the definitive paper linking the nature of Hair Ice to the presence of a fungus.  The online magazine Live Science featured a story about Biogeosciences paper entitled 'Rotting Fungus Creates Beautiful, Glistening 'Hair Ice' "  The online magazine EARTH gave a perspective on the same paper in an article entitled Peculiar Shape of Hair Ice linked to Fungus

More Examples of Hair Ice / Haareis

On the Geograph web site in the UK where the goal is to have photos of every grid square there are two images of Hair Ice from near Inverness, Scotland.  One close-up example is from the Altyre Estate and the other image shows occurrences of Hair Ice on the ground in an Altyre wood.   There is no doubt these are photos of Hair Ice, although they are not identified as such.

Figure 4 -- Rick Eppler sent me this photo from Vancouver Island, British Columbia.  I have included this image because of its content and quality.  Note the frost on some of the green vegetation at lower left and lower right. 

The Story of Snow shows two images of Hair Ice . The author notes he has been looking for such ice for years and finally found it. These images are clickable and one can zoom to see greater details. The author does not state where he found this Hair Ice but Ellen commenting on this web site noted " I've been seen hair-ice for years on alder at Mclane Creek Nature Trail & calling it hoar frost." The Nature Trail is in the Puget Sound area of northwest Washington. On this same web page the author has a simplified diagram showing how water moves up with capillary attraction to produce ice.

As a geographer I want to know what is where, such as where Hair Ice is found and why it is there.  After reading the literature and hearing from persons who have found such ice I assumed it was restricted to the Pacific Northwest in North America and western Europe.  Then I received photos from Sybil Nunn of Halifax, Nova Scotia, Canada - on the Atlantic coast of North America.  She found this Hair Ice in her area - so I must revise my assumptions.

Figure 5 -- Two of a number of photos from Sybil Nunn of Halifax, Nova Scotia.  These were seen in her local area and are definitely Hair Ice. 


The 2012 paper by Matzler, argues that Hair Ice forms on a few species of wood and is dependent on the presence of a fungus.  The 2015 paper by Hoffman establishes the link to a fungus. 

The climatic conditions that produce of Hair Ice are common in many areas in the middle latitudes.  But, Hair Ice appears to occur only in Europe, the Pacific Northwest of North America and in a few places in the eastern Canadian Provinces.  When I first starting writing about Hair Ice (which I have never seen personally) I had never heard about it in the eastern and central parts of North America.  Since then I have had confirmed reports about Hair Ice in Ontario, Nova Scotia and Prince Edward Island of Canada.  I suspect the factor limiting the geographical distribution of Hair Ice is environment in which the fungus thrives.  The tree species on which Hair Ice has been observed are more wide-spread than is Hair Ice.  It has been suggested that Hair Ice does not occur south of 45 degrees north.  I am hypothesizing from a small sample size.   We need more observations. 


Bibliography cited above with no online links

Lawler, D. M., 1988. A Bibliography of Needle Ice. Cold Regions Science and Technology, 15, pp. 295-310.

Outcalt, S. I., 1971. An Algorithm for Needle Ice Growth. Water Resources Research, Vol. 7 pp. 394-400.

Related web pages showing products of Ice Segregation

Ice Flowers - ice growing on the stems of a few species of plants

Needle Ice - ice growing at or near the top of the soil

Pebble Ice - ice growing on small rocks through ice segregation

Sub-surface ice formation in geologic environments


Reflections on a World of Ice Formations

Ten years ago I knew about icicles and patches of ice on streets and walkways, and that was about it.  Now when it is above freezing part of the day and below freezing part of the day I look for ice in many places, and often find it.  I have learned much by observing these many forms of ice.  I hope you will join me in the search for ice in its many forms. 

What we do know is that this ice is not a form of frost.  Frost comes about when the air becomes saturated and water vapor is deposited on a surface as an ice crystal.  If the air temperatures are above freezing we get dew, but when it is below freezing moisture is deposited out of the air as frost.  Certainly, in most cases the conditions that are appropriate to the growth of Hair Ice / Haareis are also appropriate to the formation of frost.  For this reason many persons who find such ice are likely to give it descriptive names such as 'silk frost.'  But the appropriate name is Haareis or Hair Ice. 

Ice segregation is the process and the products are Hair Ice/Haareis when it is on dead wood, Ice Flowers when it occurs on plant stems, Pebble Ice when small rocks serve as the medium to move water from the soil to the freezing surface and Needle Ice when it occurs at or near the top of the soil.  Thanks to Ice Segregation we have the opportunity to see some beautiful growths of ice, but we must look fast because the heat of the day takes them away. 

Thank goodness for the Internet and digital cameras for they let us capture such images and exchange photos and stories about these attractive ice formations.  Please look for interesting ice when the freeze/thaw processes are underway and share any findings with all of us.  

For my many perspectives on ice see my web pages at    Feel free to contact me at    to share your photos of ice.

One of the many web pages of Dr. Jim Carter

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