WRAL WeatherCenter Blog

I keep a small dish of water on the deck for the birds to drink from. saturday morning, the 12th, of course it was frozen. however, an icicle (?) had grown out of the water. i've seen small spikes grow out of ice cubes in the freezer, but this was much larger, and almost shaped like a bird! if anyone knows what in the world caused this phenomenon, it has to be you.

Posted December 26, 2008

MIKE MOSS SAYS:        Susan,    The ice growth from your water dish was likely a variation on the ice spike phenomenon that you said you've seen in the freezer. The shape and angle of the spike, or in some cases more complex protuberances that garner descriptions like "towers," "vases" and the like, can vary depending on the shape and depth of the container, the purity of the water and the temperature of the surrounding air (not to mention the rate at which the surrounding air cools relative to the temperature of the water).

The general idea is, in the occasional instances when ice forms across the top of the container and seals itself at the top against the edges, but some unfrozen water remains underneath, expansion of the water as it is about to freeze, and/or pressure from ice around the edges and top that has already frozen and expanded, can force water up and out through an opening or openings in the icy crust. When that water is exposed to the air, it may rapidly freeze on the outside while additional water still moving up through the initial hole remains unfrozen, and so on, building a tube-like or triangular spike, or in some cases more complex shapes, before the entire process comes to a halt when all of the water has frozen or the water inside the spike freezes the tube shut.

The phenomenon seems to occur most readily with distilled or at least relatively pure water, and with air temperatures in the 15-25 degree F range.

You can find more explanatory info on this phenomenon and some interesting photos through the addresses below, along with some of the links from those pages...






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