Hoar frost occurs when water vapor, such as fog, touches a very cold surface and freezes on it instantly.
This is called sublimation.
Sublimation is the transition of a substance from the solid phase directly to the vapor phase, or vice versa, without passing through an intermediate liquid phase according to the National Snow and Ice Data Center.
This can happen to any object that's cold enough for the water vapor to freeze on but it is usually something that has a smaller circumference. It wasn't very thick today but it was beautiful.
The word hoar has its origin in German and is taken from the word 'hehr'. 'hehr' means sublime. Later, it was adapted by Old High German as hér and meant old. The Old Norse modified it as 'harr' and meant 'grey with age'. The Old English adapted it as hār and the Middle English as hor.
Hoarfrost could then be translated to Mr. Frost.
The whole day was foggy giving Phil the ground hog, also know as the woodchuck (which is what is called in these parts), whistle pig or marmot, no chance to see his shadow. Spring should be right around the corner. Actually, we are still waiting for a proper winter to arrive, but if it doesn't come we won't be complaining.