By John Goldwood

Hair Ice forms when specific prerequisites are present: a piece of decaying or rotted wood with specific moisture content; air temperature and humidity in a narrow range; and most importantly, the presence in that rotted wood of a single-celled fungus, Exidiopsis effusa, the critical factor driving creation of these ice crystals.

When conditions are perfect, a tiny droplet of water is forced from a hole in the decayed wood and freezes. A second droplet appears from the same hole, freezes, and pushes the first frozen droplet away from the surface of the wood. This process repeats itself until a single ice strand only 0.01mm in diameter (far smaller than a human hair) may attain a length of several centimeters. The fungi present in the ice crystals prevent the ice strands from clumping together and allow the creation of this beautiful and rarely seen ice formation.

You might walk right past Hair Ice without recognizing it. We frequently have many decaying Red Alder (a preferred host plant for the fungus) branches along our trails. Our humidity and sub-freezing temperatures are often in the perfect range, and our shorter days in winter make it easy to be on the trails shortly before or just after sunrise. If the prior evening has provided little wind, you may find these incredibly delicate and beautiful creations adorning the trail, or perhaps peeking out from the underbrush a short distance away. If you are fortunate enough to discover them, take a moment to appreciate their delicate beauty – but hold your breath!