The Nature Nerd

Focus on: Ice art

Ice crystals on a window. Submitted photo.

Ice crystals on a window. Submitted photo.

VIRGINIA – This is the season when we can walk on water! We take it for granted, but we shouldn’t. You see, ice is weird! This time of year we see it every day, so we do not think about it much. In fact, ice is a very strange substance; some say it is the strangest substance in the universe. And, were it not for its weirdness, the Northwoods would be a very different place!

First, the fact that ice floats on water is unique. The solid forms of most substances sink in their liquid forms. We all know that materials of all kinds contract as they get colder. As a result, they get heavier, or more properly said, they get denser as they cool. Most substances do this at all temperatures, so they sink when they freeze. But not water. Water has the odd behavior of expanding as it nears its freezing point. Between 38 degrees and 32 degrees water expands. Consequently, it gets less dense as it reaches the freezing point and floats. That ice floats is profoundly important.

Imagine our Northwoods life if ice sank! Lakes would freeze from the bottom up. Very likely, our lakes would freeze solid, from top to bottom (or, I should say, from bottom to top). Likely, they never would completely melt. How would fish survive? How would we ice fish?!

That ice expands as it freezes is very important in many other ways. Our potholed streets are another feature caused by the expansion of water as it freezes. First, water seeps into tiny cracks in the pavement. Then, when it freezes it expands. And, it expands with great force. Thawing freezing-expanding, thawing-freezing-expanding, thawing freezingexpanding. This cycle repeats itself dozens, if not hundreds, of times each year. And the expansion is very forceful. Thus, our roads need so much maintenance.

The freezing of water has some weird underground effects too. As ice forms it draws liquid water into its crystals, where it becomes solid. Again, it expands and pushes the surrounding soil, or even stones, upward. Sometimes it forms distinct layers of ice within the soil. I have seen layers of ice a foot deep and as much as six inches thick that were absolutely crystal clear. Then, come spring these layers melt, and the result is the instability often called frost boils.

Another odd feature of water is that it can exist as a liquid, solid, or a gas simultaneously, in the same place. Water is totally unique in this way.

So, next time you go ice fishing, snowmobiling on a lake, or maybe just gazing at the ice floating in your beverage, contemplate the uniqueness of water and ice. Ice has other interesting properties too. In fact, most major universities have entire classes devoted to the study of ice and snow, usually called glaciology. Actually, this is just the beginning of this subject; this article is just the tip of the iceberg!

Jerry McCormick lives in Virginia, MN. He is a retired natural resources professional and is a selfdescribed nature nerd.

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