Photo: what is the strange ‘hair ice’ phenomenon seen in France recently?
Extremely rare formation is occurring in eastern woodlands
The smallest change in conditions can cause ‘hair ice’ to melt
iwciagr/Shutterstock
Rare ‘hair ice’ formations - frosty filaments resembling white silk which appear on pieces of dead wood - are stunning people in eastern France as chilly weather over the previous weeks have made conditions perfect for the phenomena to appear.
The thin, spindly webs of ice – called cheveux de glace or barbe de glace in French – have been spotted in the Bas-Rhin and Yonne departments.
Photos of some of the hair ice can be seen below.
What causes hair ice?
Hair ice requires near-perfect conditions to form: humidity must be at a certain level, temperatures must be around 0C and, vitally, specific species of fungi must be present.
It is in part so rare because the strands of ice are so thin – a fraction of a millimetre wide – subtle change in conditions can change its structure. This includes strong wind, sunlight, and changing temperatures.
German meteorologist Alfred Wegener – better known for his theory of continental drift – was the first to claim that the spectacle was caused by fungi, although it took until 2005 for this to be mostly confirmed and 2015 for scientific journals to publish full evidence.
The main fungi responsible for hair ice – Exidiopsis effusa – is found on dead or dying broadleaf trees, meaning hair ice only develops on rotting wood.
Despite its rarity, hair ice can be seen in gardens and woods across France when conditions permit.
As this weekend is set to see national averages significantly above February averages, do not expect to see any in the coming days.
Read more: Temperatures of 22C and rain: French weekend weather outlook February 22 - 23
