Mysterious hair ice phenomenon explained

Hair ice looks like incredibly fine, billowing strands massed together. Lasting merely hours or only a few days before melting, its exact cause has been a mystery for nearly 100 years.

But not anymore.

A team of scientists led by Dr. Christian Mätzler from the Institute of Applied Physics at the University of Bern in Switzerland, published a study in the journal Biogeosciences attributing the formation of hair ice to the common forest fungus Exidiopsis effusa.

See photos of hair ice:

Mätzler and his co-authors identified 11 forms of fungi across multiple samples of wood where hair ice was found. Using microscopy analysis, it was determined that Exidiopsis effusa was the only fungus consistently present. Mätzler believes the fungus' mycelium directly aids the hair ice in forming and holding its shape.

Hair ice grows on rotten tree branches typically on humid winter nights when the temperature is below freezing.

It was first studied by Alfred Wegener in 1918 after he noticed a collection of what looked like cobwebs covering wood. The cobwebs were fungus mycelium, and Wegener theorized it had something to do with the ice's unusual shape, but up until this point his theory was never fully confirmed.