Hair Ice

Britain is being hammered by Storm Bella except, it appears, for Golspie where, although the barometer reading is about to fall off the bottom of the scale, it's....

....a fine, if icy day. Last night the temperatures dropped to -2C and it was still -1.3C when we set out on our morning walk through Dunrobin Woods, where....

....we spotted what looked like a ball of cotton wool cast aside by an unecological litter-lout. However, on closer inspection, we discovered that it was....

....a mass of fine fibres of ice, looking incredibly like asbestos, and very brittle and easily broken.

It took moments on the internet to identify it. It's called hair ice or ice wool or - I prefer this - ice beard. It's uncommon, and only forms in very precise conditions. It occurs between 45–55N in broadleaf forests, in our case, on small, rotten, damp birch branches, when temperatures are slightly under 0C and the air is humid. The smooth, silky hairs have a diameter of about 0.02mm and are up to 20cm long The hairs can take the shape of curls and waves and may maintain their shape for days, which suggests that something is preventing the ice from melting.

In 2015 scientists identified the fungus Exidiopsis effusa as responsible for the formation of hair ice. The fungus was found on every hair ice sample examined, and disabling the fungus with fungicide or hot water prevented hair ice formation. The fungus shapes the ice into fine hairs through an uncertain mechanism and probably stabilises it by providing a recrystallization inhibitor similar to antifreeze.

Nature never ceases to amaze!

Information from Wikipedia - here.