|Needle ice |
Photo credit: Whitney McCann
Unlike rime ice, which is influenced by wind, needle ice is influenced by temperature and seen in late fall when there isn't snow cover but the air is freezing. When underground cold running water contacts a frozen ground surface, the water freezes at the interface, adds to the ice, and is pushed up through the porous soil into the atmosphere. "Roots and plants and burrows of animals are destroyed by the cutting ice," one winter handbook reports. "Needle ice is extremely powerful. If the ground is denuded of vegetation by other processes, needle ice formation can keep it exposed to erosional processes. Plant recolonization is very slow." It's forest disturbance on a small scale and another example of nature altering its own landscape.