Hair ice

Description:

In 2015, the fungus Exidiopsis effusa was identified as key to the formation of hair ice. An uncommon phenomenon - Hair ice forms on moist, rotting wood from broadleaf trees when temperatures are slightly under 0 °C (32 °F) and the air is humid and is generally confined to latitudes between 45°N and 55°N.

Habitat:

Spotted on a rotting limb in a pile of wood debris in a wooded area next to the Snoqualmie River.

Notes:

In 2015 the scientists Hofmann, Mätzler and Preuß determined the exact cause of the hair ice phenomenon, linking its formation to the presence of a specific fungus called Exidiopsis effusa. They discovered that the presence of the fungus led to a process called 'ice segregation'. When water present in the wood freezes it creates a barrier that traps liquid between the ice and the pores of the wood. This creates a suction force which pushes water out of the pores to the edge of the ice surface where it freezes and extends outwards. As this repeats it pushes a thin 'hair' of ice out of the wood which is around 0.01 mm in diameter. It is believed that an inhibitor present in the fungus allows the strands of ice to stabilise allowing the formation of the beautiful phenomena and allows the hair ice to keep its shape often for several hours.