Hoarfrost: not a moral judgement

I noticed two things when I woke up this morning.  One, it was way too dark to be time to rise and shine.  And two, it was so darn cold that there was hoarfrost on everything.  Of course I felt duty bound to snap a few pictures even though the indoor thermometer read 6 degrees F for outside.  Ugh. 

Just what is this mysterious and beautiful thing we call hoarfrost?  I have included a link to an article published by University of Alaska Fairbanks by T. Neil Davis if you want the details, otherwise a quick summation.  When air cools down it does one of two things, 1. turns to dew if the dew point is above freezing (32 degrees F) or, 2. turns to hoarfrost if the air is dry (the dew point is below freezing).  Davis mentions in his article that it occurs in different forms, including needles, plates, cups, and feather-like.  My second question, just why is it called "hoar" frost?  I flipped open the ol' Funk and Wagnells dictionary and found that "hoar" means one of three things, none of them about prostitutes.  Number three definition: "White or grayish, as with frost."  My eye went down the page a bit to "hoarfrost," which is "frost whitening the surface on which it is formed."

Part of enjoying a garden year 'round is appreciating the strange and wonderful things cold weather does to our plants.  Hoarfrost might be the only thing I can appreciate about my garden in 6 degree weather.  That and the lack of chores to do out there.