Greenbelt Lake is frozen, as are the rivers, streams and ponds of our town. They’re not frozen six-feet thick, or frozen only to be clear in the spring, but frozen over with crinkly ice that makes its own winter groans and clicking sounds.
Walking and skating on the ice are prohibited by City Code 12-66, but marveling at it is encouraged. And it is worth marveling, because ice is weird.
Icing on Top
The ice starts on the top of the lake. In the fall and winter, the lake’s water loses energy to the air. As the water cools, it gets more dense and it sinks. The fact that the cooler water sinks might make it seem like the ice should start at the bottom of the lake, but here is where it gets odd. Water is at its most dense at 39.4 degrees Fahrenheit (4 degrees Celsius). When it gets colder than that, water expands and floats up. The coldest water on the top of the lake freezes to ice. Pure ice forms at 32 degrees Fahrenheit (0 degrees Celsius). Our lakes and streams are not pure, but close enough.
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Fancying the Frozen Lake
Berries cling to some branches at the edge of a frozen Greenbelt Lake on a frigid Friday. Photo by Jill Connor.