On mild days, moisture is drawn from the snow pack into the air. Relatively speaking, warm air holds more moisture than cool so as temperatures drop at night some of that moisture is released as condensation. And if the object upon which that moisture condenses has been chilled to below freezing, frost will form on its surface.
Freezing fog (Beware the Pogonip!) can create frost and has its own eerie beauty but the best examples of frost are seen when the sky is clear and radiational cooling seems to suck the heat out of everything, hurling it out past the stars and into deep space. Delicate filigrees disappear quickly when the warmth of the sun takes over and by the time most people get up the show is over.
The lip of a bucket, left out overnight, grows a miniature forest of ice crystals.
Frost-covered trees diffuse the morning sun.
Shovel handles, picnic tables and even plastic netting are coated and, in the garden, last years stalks sprout ethereal, ghostly blooms, a chilly reminder of the months until spring. That’s nice because the way things are going January has become a bit of a slog.
The View from Fish in a Barrel Pond 