4 January 2011
A few weeks ago it was frost flowers and now another strange ice formation is spotted here in the Tennessee Valley.
This time it’s an ice spike. Merlin (Mo) Marice of Huntsville in Alabama went out to check his bird bath Monday morning and was greeted with this! He called and sent me the pic in search of an explanation.
My initial guess was that the top of the ice froze first. Then, as the rest of the water froze, the water beneath the frozen surface was forced out a small hole in the ice sheet. A hollow tube surrounded by ice forms and grows as the water rises and freezes. I did some research and even found a letter to the editor of NATURE back in the early 1930’s describing just such a spike in a bird feeder.
A little more research led me to Dr. Stephen Morris at the University of Toronto. He runs a great web page with images of these strange ice formations. Water is a really weird substance. It’s one of only a very few that actually expand as they freeze. This, along with capillary action and surface tension, (water is “clingy”) can cause these ice spikes.
Scientific American had an article on these ice spikes as well. It’s well worth a read.
In case you are interested, Silicon also expands when it freezes. It freezes at 1,414 degrees C. So we do not often observe the effect!
Update: Marice says it happened again today and the spike was larger. Will update with a pic if possible.