Hunting Haareis

Day 104: They say timing is everything, and with a few years of experience behind me, I've gotten fairly good at predicting when the haareis ("hair ice") will emerge at Big Bridge. Conditions have to be perfect for its formation, a Goldilocks combination of temperature and humidity, and of course the presence of the fungus Exidiopsis effusa which is the most important component. The exact mechanism is unknown, but the general idea is that Exidiopsis forces moisture out of decaying wood following the medullary rays of the wood's structure, thereby creating threads of ice which may attain lengths up to eight inches. The longest I've personally seen would have been about two inches. The ones in this photo measure a little over an inch in length.

Now here's the story. I know where Exidiopsis lives in the general vicinity of Big Bridge, off trail and through an obstacle course of blackberry vines, salmonberry thickets, reed-canary grass and fallen logs. As I mentioned yesterday, I sent up a plea to the Frost Spirits, asking them to provide a good example so I'd have something to post on my blog. To that end, I parked the car and set off at a dead lope along the mile to Big Bridge. I was nearly there when I spotted one small tuft at trailside and, afraid it might disappear if a ray of sun hit it, I took pictures before continuing on to the main site. The core of Exidiopsis country yielded up a few more small specimens, and by the time I left the area, I was satisfied that I had material for a post. I took my time getting back to the car, and since at that point I wasn't so goal-oriented, I was more observant. Roughly a tenth of a mile from parking, I spotted a larger, more intricate cluster of haareis and the beautiful example shown above. Even closer to the car, I found more right along the side of the trail. I had been so intent on my mission that I'd gone right past the best of them all in my haste to reach Big Bridge. 

At Big Bridge

Day 102: In the hopes of finding more elaborate examples of haareis (hair ice), I took a walk out to Big Bridge yesterday, but with the clarity of hindsight, I know now that I should have waited another hour or two for the frost to melt. I found only a few small formations, widely dispersed, and no more than an inch long. That said, it was a lovely but chilly hike of a little over a mile to the bridge on hard-frozen ground. I have to admit it was a relief not to be travelling it when it's muddy. As part of the Nicholson Horse Camp trail system, the path gets pretty well chewed up by horse hooves, and there are almost always abundant equestrian "land mines" to dodge. Still, Big Bridge is my number-one site for haareis, and at this time of year, most of the horsey crowd is staying at home. The photo on the left was taken facing west from the bridge and shows the area where haareis appears. The photo on the right is the view to the east.

Finding Haareis

Day 100: Hair ice has been on my mind for the last several days, given recent weather conditions, but I have to admit I wasn't thinking about it when I set out for a short walk in a local county park. I was near the top of the one-mile loop when I spotted the first piece alongside the trail, and my jubilant cry of "Haareis!" must have been rather bewildering to the couple walking their dog the opposite direction. They weren't curious enough to ask as they passed me by, but by then, I had already taken pictures and I doubt that they even looked down to see what had grabbed my attention. A little further on, I spotted another example of this fascinating phenomenon. You see, true haareis (hair ice) forms only in the presence of a specific fungus, Exidiopsis effusa. It occurs on decaying deciduous wood and only under certain conditions. Although the precise mechanism of the fungus' role is not understood, it has been suggested that it may provide a natural antifreeze which stabilizes the formation of ice crystals. It has been noted that the ice "hairs" form at the openings of medullary rays (a cellular structure formed in active cambium, perpendicular to the growth rings of the plant). The "hairs" are also similar in diameter to the medullary rays (roughly 0.02 mm). It should not be confused with ground frost (a type of hoar frost which forms in soil).

Hair Ice

Day 102: Hair ice (aka haareis or frost-beard) occurs only under certain conditions, all of which I felt sure were present this morning, and I was not disappointed. This unusual and beautiful ice formation is most likely to be found in northern broadleaf forests. Although temperature and humidity play major roles in its development, the most crucial element is a fungus called Exidiopsis effusa which provides the "scaffold" on which the ice crystals form. The fungus' role is not completely understood, but it has been suggested that it may provide a natural antifreeze which stabilizes the formation of ice crystals. The ice "hairs" form at the openings of medullary rays (a cellular structure formed in active cambium, perpendicular to the growth rings of the plant) and may attain lengths up to eight inches.