What IS hoarfrost?

I've had lots of folks ask what hoarfrost is, so here's the definition: "A deposit of needle-like ice crystals formed on the ground (and objects) by direct condensation at temperatures below freezing point. Also called white frost." Hoar derives from Hoary (both Old English words), meaning grey or white, as if from age; ancient. Hoarfrost is a common earthscience term for this type of freeze. Here are some close ups of the frost. Very pretty and quite interesting.