The other day my friends Jon, Alee, and I went on a moonlit cross country skiing adventure at Sidie Hollow Park. The bank in town said it was 11°F outside but at Sidie Hollow, by the lake, it was most certainly colder. As we skied the trail alongside the lake, it was easy to feel like we were out in the deep wilderness. Rarely do I feel that way since moving to SW Wisconsin, a place with very little public land for hiking, so I was taking it all in. I was struck by how incredibly bright it was outside with the near full moon and layer of snow on the ground. Thanks to the wind during the recent blizzard there was no snow on the lake which made it look eery and still. As we rounded the first bend in the lake I was introduced to the phenomenon of lake singing and, for lack of better words right now, my mind was absolutely freaking blown. Seriously.
The first noises we heard were like a low humming. Never having heard such a thing before, I think I just tuned it out and didn’t give it much though. But Nature didn’t want me to tune this fantastic sound out and the next sounds were LOUD and startling. The only way I can describe it is like a low humpback whale song combined with loud vibrations and cracking noises. We continued skiing around the lake, stopping every once in a while to warm our hands and take in the beauty and stillness of the night. At one point when we had stopped to listen to the noises, one was so loud that we all jumped. A crack or shift in the ice happened directly in the front of us while we were watching. I could feel the vibrations in my body. A dozen owls hooted in the distance as if responding to the ice. Alee made a joke that in Wisconsin we stand around and listen to the lake freeze. We all laughed because we knew there would be no way to ever explain this phenomenon to anyone who had never experienced it. It was seriously one of the most fascinating and magical things I have ever experienced.
Upon hearing the noises I was first met with wonder and awe. It was absolutely magical and completely mysterious. My next thoughts turned to science– why is this happening? Did it have to do with expansion? Water is less dense as a solid so maybe it has to do with that. Or maybe it has to do with the low temperature outside. Does the lack of snow cover on the lake make then louder? It amazed me how quick my mind went from magic to science and in a way it bothered me. Am I unable to see the magic in nature now? Has science ruined me? Of course not! It is my background in science and my love of the outdoors that made this all the more exciting the me! Of course the noises were absolutely mind blowing but knowing how nature does it is also mind blowing. This is why I love outdoor and environmental education! Because it’s all about teaching folks to see magic in the outdoors! It’s about facilitating an experience that inspires wonder and awe and encouraging them to ask meaningful and insightful questions. It’s about encouraging curiosity about nature and the world around us. I would argue that environmental education can’t exist without both magic and science in some combination.
So why is it that the ice sings on a frozen lake? The answer has been harder to find than I expected and many of the answers are actually just theoretical. It could be changes in atmospheric pressure or temperature fluctuations. It might have to do with the moon. Whatever scientific answer is it will not change this one fact to me: skiing under a full moon and listening to the lake sing was absolutely magical.
If you are interested in learning more Dispersion of Sound Waves in Ice Sheets by Andreas Bick has great information as well as links and sound recordings. The best way to learn more is to get outside and experience it for yourself if you can. It will definitely be worth braving the cold!