Scientists have long tried to identify the culprit responsible for the formation of white hair ice. Though you may not be familiar with the term, such formations aren’t that rare. The freakishly white hair ice found on rotting tree branches is produced by a fungus called Exidiopsis effusa.
The team of researchers responsible for making the discovery published their findings in the scientific journal Biogeosciences.
According to the researchers, the delicate strands of hair-resembling ice appear as a result of a complex process, involving specific weather conditions. This 100-year-old mystery was solved because of Christian Mätzler’s curiosity, from the University of Bern, Switzerland, sparked during a forest walk. Mätzler and his team began investigating the process by conducting a multitude of tests, from melting the ice strands to attempting to produce it themselves.
Before Mätzler, Alfred Wegener attempted to understand how this hair ice form. He theorized that a mycelium must be responsible for the curious ice formation. Now, Mätzler managed to prove Wegener’s theory. He and his team proceeded to treating rotting tree branches with scalding water. By killing the fungal populations within the branches they treated, they ensured that hair ice would no longer be produced.
According to Mätzler, if the fungal populations aren’t present in the wood, ice forms at the same rate, but as a crust-like structure.
With the help of biologist Gisela Preuß, the team of researchers identified the responsible fungus. Preuß began examining samples of the ice strands collected in three consecutive winters (2012 through 2014). By investigating which species of fungi were populating the rotting wood, Preuß noted that one particular one colonized all the samples of wood that had been producing hair ice. Exidiopsis effusa.
“The action of the fungus is to enable the ice to form thin hairs – with a diameter of about 0.01 mm (0.0004 inches) – and to keep this shape over many hours at temperatures close to 0°C (32°F),” the research team explains.
According to the team’s hypothesis, the fungus is responsible for producing a sort of recrystallization inhibitor that stabilizes the ice hairs and allows them to form as they do. Preuß explained that the ice hair form during the night and melt again once the sun shines on the rotting wood.
Photo credits: epod.usra.edu