Beard Frost

When temperatures are above freezing water vapor (dew) can condense and collect on grasses, branches rocks and other surfaces.

If the temperature falls to freezing (or below) the dew can take the form of a white covering known as frost.

A feathery form of frost phenomena occurs when climatic conditions (typically overnight) are such that crystalline spicules grow from water vapor in the air upon the freezing surface of solid objects.  

This is called desublimation (changing directly from a gas to a solid with no intermediate liquid phase).  The air must be humid, but not so humid that solid ice forms.  Wind moves the humid air over frozen objects causing frost spicules to form.  The size of these feathery crystals depends-upon the temperature, the amount of water vapor in the air and how long they are allowed to grow undisturbed.  The result is called hoarfrost.  

The word hoar derives from old English and refers to the old age appearance of the ice crystals that mimic white hair or a beard.

Jack Frost was rather busy overnight as we woke to a crystalline wonderland.

After breakfast the dog and I scored more than 40 photos of this wonderment on our walk today.

Here are a handful...

click on any image for a closer look