The ice cometh: The hard work of freezing

In freshman high school science class my teacher led us through a simple but enlightening experiment to show the difference between water and ice. It’s worth describing as we wait for our lakes to freeze over, likely in a month or so from now.

The teacher had us half-fill two glasses with water. Into one we dropped an ice cube, and into the other an equal volume of ice water. We then recorded the temperature of the water in both glasses for half an hour.

In the glass that received the ice water, the temperature dropped instantly, but then began rising and kept doing so. In the glass that received the ice cube, the temperature dropped more slowly, but then bottomed out and stayed down as the ice melted. The teacher then asked: Which would be the better way to cool a drink on a summer day?

The answer was obvious. What the experiment illustrated was a property of water called the heat of fusion, which will soon come into play on your lake and mine. Heat of fusion for water is the amount of heat energy that has to be removed to turn it from liquid to ice.

The definition of a calorie is the heat required to raise the temperature of one gram of water by one degree Celsius. It turns out that it takes a great deal more energy to turn water into ice than simply to change its temperature. In fact, 80 calories must be removed from that one gram of water in order to freeze it – and during the process the water’s temperature doesn’t change.

This works in reverse, too: It takes 80 calories to melt a gram of ice. In other words, it takes 80 times as much energy to melt ice as to warm water by one degree; or the same energy to melt ice as to warm water from zero degrees all the way to 80 degrees Celsius.

Now, let’s think about our lakes. As the days and nights get colder, the water temperature is dropping, rather quickly. Overnight low temperatures are now routinely below the freezing point of water, which is zero degrees Celsius (32 degrees Fahrenheit). So, why don’t our lakes freeze sooner? It’s because of that heat of fusion.

The water temperature will get down near the freezing point fairly quickly, but once it does, the water must give up a very large amount of heat energy before becoming ice. Finally, as the days and nights keep getting colder, we’ll see ice crystals forming along the shore, then a skin over the shallows, and finally, after a very cold, still night, a sheet of ice over most or all of the lake.

I saw the ice go off our lake last May. This year will be my first chance to watch day to day as a lake freezes. I am looking forward to it.

Wind, leaves, needles, walleyes

If you went down to your lake yesterday, you no doubt saw its near-shore surface decorated. About noon a strong wind arose, breaking the now-tenuous bond between leaves and their twigs.

As I walked the 57 (yes, I’ve counted) steps down to Birch Lake, near Harshaw, Wis., oak leaves drifted by, sliding through the air like paper airplanes. Maple leaves spiraled down. Brown clusters of discarded white-pine needles littered the stairway. Around the pier, those same items dotted the water and lay on the bottom.

I had never fished this late in the season before – have you? It’s a beautiful way to watch the season wind down. The sun, amid gray clouds, slowly settled toward the woods. The trees to the east (mostly the oaks) still bore their colors, though less brilliantly, and more sparsely. As I anchored over my favorite reef, the wind, less energetic than earlier in the day, put what anglers call a “walleye chop” on the surface. Between my boat and shore, a musky angler drifted by, tossing a slender crankbait.

It soon became clear I had some things to learn about this late-fall fishing. The walleyes still haunted the reef, which rises to five feet below the surface, from 17 feet on the deep side and 10 or 12 toward shore. It took just a few minutes for the first walleye to grab a minnow and pull my chartreuse-topped slip bobber down. I waited to a count of 10, then yanked back on the rod and...nothing. I reeled in the minnow, still lively.

I cast out again. The bobber soon disappeared. I counted to 15...nothing. Next cast, count of 20 and...nothing. In summer a five-count was enough. These fish were behaving differently. I pictured the walleyes swimming slowly, mouthing the minnow, as if savoring before swallowing.

I learned to wait until a count of 30, or 40. I ended up with two keepers in the livewell, both lip-hooked even after the long delays. Given that much time in summer, the fish would have gulped the minnow down, the hook embedded deep in the throat, a situation to be avoided.

The lights went down on the evening, until I could barely see the bobber on the wavelets. It slid under the surface, and I waited. My basketball coach used to say always to end a practice on a made shot. I wanted to end my season with a caught fish (because, in all likelihood, this was my last outing of 2013).

I counted: 20...30...40... 45. Set! The season’s last fish – a 9-inch walleye. Lip-hooked. Released unharmed. I motored at low thottle through the semi-dark to the pier. On the way up the stairs I could half-see, half-feel, oak leaves still gliding down. The two walleyes? They'll be frozen and saved for a winter fish fry -- in memoriam.

What color are your lake’s loons now? Are they still around?

Long years ago a friend and I took our first autumn fishing trip, to a Northwoods lake we usually visited in June. As we set up on our fishing spot on a chilly mid-October morning, a bird popped up near our rowboat. It had a shape like a loon – the graceful neck, the long, pointed bill – but its colors were different, the sleek black of the head replaced by brownish gray, the spots now sparser and on a gray background.

Something told me even than that is was a loon, in its winter plumage. I’m not sure how I knew; perhaps because no other bird (in these parts anyway) has that distinctive shape, and I knew loons haunted the lake where we were fishing.

Have your lake’s loons changed their plumage? In all likelihood they have. I saw a loon in winter dress as far back as September 6, on a small wilderness lake in Wisconsin’s Northern Highland-American Legion Forest. There was a loon on our Birch Lake (near Harshaw, Wisconsin) as late as last Saturday, Oct. 5. I never got close enough in the fishing boat to see its markings; it was more skittish than loons on our lake usually are (and anyway, as ethics require, I didn’t pursue, only hoped our paths would cross close enough to allow a good look).

I’ve wondered: How exactly do loons change their plumage? It seems to happen pretty quickly. I’d seen September loons on our lake in summer attire, then that specimen on the backwoods lake decked out for winter. Well, it turns out the color changes through molting: Summer feathers fall out to reveal winter ones grown or growing in. At the same time, the loons' eyes lose their bright red and fade to brown. They also pretty much quit calling.

Neighbors here on Birch Lake have expressed concern for the remaining loon, which they say should have left by now. I suspect there is still plenty of time; there is no risk yet of the bird getting iced in, and won’t be so long as enough water remains open for a long runway. As it keeps getting colder, this loon and others will head south toward the ocean for open water and a ready food supply. Loons gather in groups during migration – as many as a hundred, or even more. That would be a sight worth seeing.

Keep an eye out for your lake’s loons – if not gone already, they soon will be. They won’t start their journey back until February or March, and they’ll time their arrival here for just after ice-out. They’ll be dressed for summer – wedding attire.

Closing time

This season for me begins the fulfillment of a dream: To spend an entire year on a Northwoods lake. Of course, this is now our one and only home, so with luck that year will turn into many. For now we enjoy the magic of peak fall color reflected in water.

Do you live at your lake? Stay for the summer? Visit for the occasional week or weekend? Until this year I had never been here in the north to experience the slow turn toward winter. Right now we’re on the brink. Have you seen your lake this way? We’re torn between carving out a few more fishing days and giving up, pulling in the pier and buttoning the boat up for storage.

Recent evenings it has been mesmerizing to watch a slip bobber float on a gently undulating palette of reflected oranges, yellows and reds. Such evenings now are numbered. Yesterday I took the last dozen minnows, anchored the boat on a favorite reef, and tried once more for the walleyes and smallmouth bass that haunt the rocks. The sky threatened. Wind poked through my fleece jacket. Waves tossed my bobber around. Nothing bit. This could be the time when the fish retreat to the depths and become harder to find. Or a few more warm days could intervene and change the pattern.

Back at the pier, the boat tied off, I sat on our bench and scanned the shore. The trees lining the lake had taken longer to turn than those at the top of our hillside, but now they blazed, especially when for a few interludes the sun pierced the gray sky. Years ago my father, returning from two weeks in Norway, said that so much beauty, seen everywhere, brought a kind of fatigue. I feel that way now, not just viewing fall’s majesty but surrounded by it, immersed in it, splashes of brilliance outside our every window, around every bend in the road, arcing over our narrow private road and the town roads I travel on bicycle. It is fleeting, I know. We are just a few days, or a frigid night, or a strong wind, from lights out, the trees suddenly bare, the ground a colored kaleidoscope for a few days, then brown.

So if you are visiting your lake now, even if you have been through all this before, get out and see it. Autumn is closing down. Winter closing in.