Hoarfrost--not as naughty as it sounds!

decorahnews.com reporter Bob Felde has been noticing a lot of people talking about "hoarfrost" recently, which got him wondering about the term.

"Hoarfrost" describes a particular type of frost--the deposit of ice crystals on objects exposed to the air, such as tree branches. We've had several days where the trees in Decorah have been covered with this type of frost.

"Hoarfrost" is formed by the direct condensation of water vapor into ice at temperatures below freezing. Hoarfrost needs two conditions to form: the temperature must be below 32 degrees and the air must be damp enough so that it reaches saturation when cooled.

Hoarfrost, and frost in general, is created by having moisture in the atmosphere transform directly from vapor phase to frozen phase--in other words, it goes directly from gas to solid and skips the liquid phase.

Now that you know what the word describes, take a look at some pictures of "hoarfrost" in Decorah.

The view north on Day Street