Winter scenery is at its most spectacular when trees, shrubs, fences, anything and everything become covered in a white layer of ice. If the sun is shining, almost any view is calendar quality. There are two very different processes that cause this: hoarfrost and rime. Hoarfrost is when ice crystals grow from high humidity in the air. The ice is actually a deposition of moisture directly from humidity in the air. This leads to the most delicate formations because the ice growth is entirely crystalline.
Rime happens when the air is foggy and the fog is made of supercooled water droplets. Supercooled means the droplets are liquid despite being colder than 32 degrees. Rime formations tend to be a little chunkier up close, but either method yields spectacular visual results. There is an old myth that a heavy winter frost foretells rain some weeks or months later. The time varies depending on the teller, but there is no connection. Winter fog does not predict summer rain.