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.