Great Egret

Great Egret

Sunday, 12 March 2017

Ice is nice

Now that it is unseasonably cold again, at least for a few days, this post may not seem so out of place.

Most people like ice, one way or another. Some like it in their drink of choice. Some like it to skate on. Or fish through. Or go ice-boating or snowmobiling on.

Some photographers find ice to be very photogenic.

Outdoor ice can be fickle if one's desire is to play a bit of pond hockey, especially in a 'winter' like we have just experienced.

Ice, just like its liquid state, is remarkable for a whole lot of reasons. One of the most remarkable aspects of water is that as it gets colder, it gets denser and heavier, and is heaviest at about 4C. I remembered this fact from my high school days, but was reminded in a very practical way one time a few years ago. One of my colleagues and I had chartered a fishing boat late in the season to get to one of the islands in the western basin of Lake Erie to do some field work. The captain wanted to know exactly how much travelling we needed to do, since because the water was much colder, and denser, than it was in the summer, it took more fuel to operate the boat and he didn't want to get stranded!

The colder the water, at least down to when it gets to 4C, the heavier it is, and the lower in the pond or lake it gets. Anyone who goes swimming knows that the water is always colder near the bottom, unless it has been quite wavy, mixing the water. When the water is calm, it settles into layers, with the warmest layer always at the top.

Once water gets to be a temperature lower than 4C, it gets lighter, returning to the surface and may eventually turn to ice. That is why ice cubes float in a glass, and a pond or a lake is covered with ice rather than freezing from the bottom up. If it froze from the bottom up, it could freeze solid, destroying all the life in the pond or lake. But with the ice on the top, sometimes covered by an insulating layer of snow, the ice and snow protect the water and life underneath from long term and perhaps bitter cold. Since the water at the bottom of the pond or lake is a bit warmer than at the surface, that is why ice fishermen sometimes see a Snapping Turtle crawling along on the bottom, or they catch a Mudpuppy (a type of salamander) nibbling away at the worm or minnow on their line. Both turtles and mudpuppies are cold-blooded, but apparently able to function in temperatures just a bit above freezing.

Just something to think about, next time you are enjoying the tinkling of ice cubes in your favourite beverage on a warm summer day!

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