Hoar-frosted Sumac

Hoarfrost forms when water vapor in humid air skips the liquid stage and freezes directly into ice crystals upon contact with objects below freezing. This process, called desublimation, occurs on cold, clear nights under calm winds.
​Unlike rime ice, which looks like solid crust, hoar consists of delicate, interlocking hexagonal structures that resemble feathers or needles. It coats trees, wires, and blades of grass in a white, crystalline fur. While beautiful, hoar on snowpacks creates a dangerous "hidden" layer that acts like ball bearings, significantly increasing avalanche risks once buried by new snow.