A family out walking in Drumboe Woods near Stranorlar during the cold snap were intrigued by a very unusual sight.
Kathleen McGarry said: “I’ve never seen anything like it. These ice formations were everywhere. They looked like feathers and felt really soft, but then it melted it your hand. It was very strange.”
The McGarry family took photographs of these strange ice feathers. On returning to their home, they set about finding out more.
They found the following explanation on the Met Office website: “Hair ice is a rare type of ice formation where the presence of a particular fungus in rotting wood produces thin strands of ice which resemble hair or candy floss.”
One of the first records of the phenomenon was made by Alfred Wegener (the discoverer of continental drift) in 1918. He observed a strange ice forming only on wet dead wood and proposed a theory that a specific fungus must be the catalyst for the smooth, silky hairs of ice.
It would be almost 100 years before the specific fungus was identified. In 2015 scientists linked the hair ice phenomenon to a fungus called Exidiopsis effuse.
When water present in wood freezes, the fungus creates a barrier. Liquid then becomes trapped 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. It then freezes and extends outwards. Repetition of the process gives an appearance of hair to the ice which is only around 0.01mm in diameter. An inhibitor in the fungus stabilises the formation, allowing hair ice to hold its shape for several hours.
According to the Met Office, the conditions required for the formation of hair ice are extremely specific. That is why sightings are rare.
To form, moist rotting wood from a broadleaf tree is required with the presence of moist air and a temperature slightly below 0 °C.
Mrs McGarry said: “I had never seen or heard of it before, but that day in Drumboe there was a lot of it. It was really strange.”
Given the rarity of the phenomenon, it really was a case of being in the right place at the right time for the McGarry family.
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