Biogeosciences, 12, 4261–4273, 2015 www.biogeosciences.net/12/4261/2015/ doi:10.5194/bg-12-4261-2015 © Author(s) 2015. CC Attribution 3.0 License. Evidence for biological shaping of hair ice D. Hofmann1, G. Preuss2, and C. Mätzler3 1IBG-3: Agrosphere, Institute of Bio- and Geosciences, Forschungszentrum Jülich, Jülich, Germany 2Birkenweg 7, 57555 Brachbach, Germany 3Institute of Applied Physics, University of Bern, Bern, Switzerland Correspondence to: D. Hofmann (
[email protected]) Received: 07 January 2015 – Published in Biogeosciences Discuss.: 02 April 2015 Revised: 11 June 2015 – Accepted: 15 June 2015 – Published: 22 July 2015 Abstract. An unusual ice type, called hair ice, grows on 1 Introduction the surface of dead wood of broad-leaf trees at tempera- ◦ tures slightly below 0 C. We describe this phenomenon and 1.1 Characteristics of hair ice present physical, chemical, and biological investigations to gain insight in the properties and processes related to hair ice. Tests revealed that the biological activity of a winter-active One of the most exciting types of ice takes the shape of fine fungus is required in the wood for enabling the growth of hairs (diameter near 0.02 mm, length up to 20 cm). It can be hair ice. We confirmed the fungus hypothesis originally sug- observed in forests, on dead wood, usually on the ground gested by Wegener (1918) by reproducing hair ice on wood and sometimes on trees that are still standing (Fig. 1). This samples. Treatment by heat and fungicide suppresses the for- so-called hair ice or ice wool grows on the surface of the mation of hair ice.