p.archdale's picture

Ice on branch

Observed: 1st November 2012 By: p.archdale
2012-11-01 07.41.31

Ice crystals formed on a piece of wood. Temperature recorded on my weather station at the time was -0.8C, the lowest overnight. These crystals were much larger than any of the rime nearby. Pocket knife is 72mm for scale.
I have seen this on other occasions and I believe it may be caused by a fungus in the wood. Can anyone tell me if this idea is right and, if so, what purpose it serves the fungus?


Caution: Do NOT use iSpot to identify fungi to eat!

Some fungi are very poisonous so a mistaken ID could have serious consequences.

  • Haareis
    Confidence: I'm as sure as I can be.
  • Ice (Di-hydrogen Oxide)
    Confidence: I'm as sure as I can be.
    Likely ID
    Ice (Dihydrogen oxide)
    Confidence: I'm as sure as I can be.
Species interactions

No interactions present.


andrewktaylor's picture

Haareis ("Hair Ice")

I've seen this phenomenon a couple of times at home on Dartmoor and have also been absolutely baffled by it - a single iced-up branch covered in hair-like ice when nothing else around has any ice on it at all. However I recently chanced upon a detailed website on the subject. Caused by peculiar micro-climatic freeze-thaw processes, possibly assisted by the presence of a fungus. I haven't fully understood how it all works yet but the pages have some stunning photographic illustrations. Here is the link: http://my.ilstu.edu/~jrcarter/ice/diurnal/ (or Google "Ice Formations with Daily (Diurnal) Freeze/Thaw Cycles")

AK Taylor

p.archdale's picture

Thanks for the link, which

Thanks for the link, which definitely shows examples of the ice that I saw. The link also took me to a German scientific paper;
Hair Ice on Rotten Wood of Broadleaf Trees – a Biophysical Phenomenon (Gerhart Wagner und Christian Mätzler, University of Bern, 2008) http://www.iap.unibe.ch/publications/download/3152/de/
Hair-ice or ice-wool formations on rotten and wet branches of leaf wood (beech Fagus, oak Quercus, and others) can appear at temperatures slightly below 0C. A satisfactory understanding of the phenomenon is still missing. In the present study we describe the phenomenon and review the associated literature, and we distinguish hair ice from related forms, such as ice ribbons or ice flowers and needle ice. In contrast to ice needles and ribbons, hair ice appears to be related to a special fungus activity. We tested the fungus hypothesis of Wegener (1918), and we succeeded in reproducing hair ice during many frost nights on beech-wood samples, which had been collected in different forests in Switzerland. Treatments of wood samples by heat (boiling water), alcohol, and most effectively by a fungicide, suppressed the hair-ice formation (Figures 16-17). Based on the analysis of the observations and experiments we came to the following conclusions:
- The origins of the hair-ice forming processes are winter-active fungi in the decaying wood, mainly in the nutrient-rich wood rays. Various forms of asco- and basidiomycetes were identified.
- The fungus decomposes the nutrients (carbohydrates, lipids) by aerobic dissimilation whose end products are CO2 and H2O. - The gas pressure of CO2 expels the stored and the produced water through the radial channels of the rays to the wood surface.
- Organic material contained in the expelled water acts as a freezing catalyst for rapid ice formation at temperatures slightly below 0°C near the exit points.
- The organic matter contained in hair ice can attract insects.
- At the onset of hair-ice melt a very thin organic fibre becomes apparent which carries pearl-like water drops.
- After severe damaging or extinction of the fungus, or when no nutrients are left, hair-ice formation stops and is no longer possible.

We need a physicist here!