http://www.its.caltech.edu/~atomic/snowcrystals/frost/frost.htm
Frost Flowers
Some of the stranger ice formations you're likely to find in the woods are called "frost flowers" or "feather frost". A typical example looks like a small puff-ball of cotton candy, a few inches across, made up of clusters of thin, curved ice filaments.
Frost flowers usually grows on a piece of water-logged wood, as shown in the pictures at right (taken by Nick Page; provided by Alan Rempel). It's something of a rare find, meaning that conditions have to be just so before it will form.
Not much has been written on this unusual phenomenon, and to my knowledge it has never been reproduced in a controlled laboratory environment. It appears that the ice filaments are essentially pushed out from pores in the wood as they freeze.
It's something of a misnomer to call this frost, by the way, since it freezes from liquid water, not water vapor.
Frost Flowers
Some of the stranger ice formations you're likely to find in the woods are called "frost flowers" or "feather frost". A typical example looks like a small puff-ball of cotton candy, a few inches across, made up of clusters of thin, curved ice filaments.
Frost flowers usually grows on a piece of water-logged wood, as shown in the pictures at right (taken by Nick Page; provided by Alan Rempel). It's something of a rare find, meaning that conditions have to be just so before it will form.
Not much has been written on this unusual phenomenon, and to my knowledge it has never been reproduced in a controlled laboratory environment. It appears that the ice filaments are essentially pushed out from pores in the wood as they freeze.
It's something of a misnomer to call this frost, by the way, since it freezes from liquid water, not water vapor.
Bart vS - Hamburg / Wageningen