This has got to be one of the strangest things I have ever seen. I was walking in our woods this frosty morning and came upon this old Alder branch that had fallen to the ground. At first I thought this was a fungus that I had never seen before, but I broke off a piece and it literally melted on my fingers - this strange sculpture is made of ice finer than a human hair! The only thing I can figure is that moisture inside the branch was forced out into the freezing air through extremely small openings. The entire 'frost beard' is about 6" long and 2" high.
Here is a link to a You Tube video that I made: http://www.youtube.com/watch?v=EuyViwX9CCk
Same branch, different frosty morning (2-18-2011). When this picture was taken, temperatures had been below freezing for only 2 hours which probably explains why this ice formation is only 1/4" high.
After 15 minutes I went back to check on the ice and to my amazement it had doubled in height to 1/2"
Today (2-20-2011) again had the right conditions for silk ice formation; the picture below shows the same branch as the previous two sessions
I searched our property for more examples and out of the hundreds of Alder branches on the ground I found two more branches with silk ice:
Closeup of ice strands exiting the third branch that I found.