Correction: The original version of this article described the ice photographed at Shenandoah National Park as hoar frost. While it resembled hoar frost, it is more accurately described as rime ...

The interaction between the warmer wet air and the cold dry air just above it, can condense as hoar frost-like crystals on the ice surface. This process requires very little to no wind.

One reference compares it to an old man's stately beard. Hoar frost crystals are 'gray' or 'silver' in color, and can be magnificent. They form when humidity is fairly high and temperatures drop ...

Sub-freezing temperatures resulted in the formation of hoar frost in Guelph, Ontario Tuesday morning. Weather Network meteorologist and stormhunter Mark Robinson captured the phenomenon on camera.