Wednesday, December 11, 2002

Hoarfrost: a deposit of interlocking ice crystals (hoar crystals) formed by direct sublimation on objects, usually those of small diameter freely exposed to the air, such as tree branches, plant stems and leaf edges, wires, poles, etc., which surface is sufficiently cooled, mostly by nocturnal radiation, to cause the direct sublimation of the water vapor contained in the ambient air.

Sublimation: the transition of a substance from the solid phase directly to the vapor phase, or vice versa, without passing through an intermediate liquid phase.

That's what it is and how it came to be...

jim