The Lake Where You Live

As the ice firms up on Birch Lake we hear the sounds collectively known as booming. But that term doesn’t begin to describe the winter music to which we’re treated as lakefront residents.

One reader recently wrote, “Last night it rumbled all night long, so loudly that I could hear it inside the house. Depending on the winter temperatures, it bangs, booms, growls, squeals and even makes shotgun sounds. In the spring, it tinkles and squeaks and makes zing-zing-zing sounds.”

I remember an afternoon last year when, while I fished with a friend, the lake played a concert. The booms weren’t like the toneless bangs of a bass drum, instead a collection of enchanting deep tones in the range of roughly half an octave, some distant, others close by. 

At times it was like notes of an Ewok’s horn on the moon of Endor, the tone repeating not as an echo but a reverberation in the ice sheet. There were deeper tones like those from a kettle drum, midway between music and pure percussion. 

Sometimes the sound resembled the gulp of a giant marine creature swallowing prey. And then came successions of notes of differing pitch and duration that I could imagine as words from an undersea conversation of whales. Some booms came with the hiss of ice fracturing: A crack that sizzled past where I sat was unnerving, though I knew it didn’t signal hazardous ice. 

Why all these different sounds? John A. Downing, director of Minnesota Sea Grant, explain on the organization’s website. He suggests we think about lake ice “as a very large drumhead or a giant audio speaker.” Some sounds arise as the ice flexes under weight. Abrupt changes in the ice create a surface vibration that then fades with friction from the air and water.

Then there’s shrinkage and expansion: as ice cools, “it shrinks away from the sides of the lake that constrains it, and as it warms it expands to push back against the shore…For a round lake of about a mile across, warming 20 degrees F would expand the ice sheet by about four feet. 

“That expansion causes the ice to crack and deform, and this causes vibration of the ice that you hear as sounds. Likewise, when it cools again it will contract, crack and deform, making similar sounds. Warming by 40 degrees F would expand the ice by almost 10 feet; that force needs to be dissipated somehow, so singing and growling ice is the result.”

There’s less booming in winter, Downing says, because the ice is thicker and less prone to fracture, the sheet weighs more and so vibrates less easily, and heavy snow on top the deadens sounds. So, that explains some of the music, though not all.

In any case, my friend and I fished on, surrounded by the lake’s melodies. As daylight faded, I forgot the fishing for a moment and just enjoyed the sounds pulsing through the chill air. It was a bit like taking time now and then, while busy cooking dinner, to stop and listen to the Christmas carols playing on the stereo at background volume. 

That night, waking for an interval, I’m sure I detected through the glass of the sliding doors, a few more wondrous notes from the Birch Lake ice.

Ted Rulseh resides on Birch Lake in Harshaw and is an advocate for lake protection and improvement. His Lakeland Times and Northwoods River News columns are the basis for a book, “A Lakeside Companion,” published by The University of Wisconsin Press. Ted may be reached at [email protected].