Here at Voyageur Quest, we love watching the lakes freeze.
It is a very exciting time of year because it means that soon we will be able to travel on water! That is, frozen lakes.
We look forward to travelling by foot and crossing over water by snowshoe or skis. Adventuring to various spots and checking out scenic landscapes & snow-covered winterland is our top priority. When the weather is nice, we even go ice fishing! And we can do this all from the comfort of or cozy, winter cottages. But how do lakes freeze and how do we know it is safe to go on them?
Usually, in summer, lakes have warm (low density) water on top and cold (higher density) water at the bottom. This is why when we stay on the surface while swimming we usually feel warmer. And when we dive deep to see if we can touch the bottom of the lake we feel cold.
As Fall rolls in, the upper layers of water begin to cool, breaking down this density difference. Believe it or not, water is most dense at 4C. So when the surface water reaches 4 degrees, it sinks to the bottom of the lake, which brings the now slightly warmer water at the bottom to the surface.
This process continues until the surface water reaches a temperature below 4 degrees. At this point, the water becomes less dense once again and begins to freeze. Remember, water is most dense at 4C; if it was at a solid state, lakes would freeze from the bottom up.
Another fun fact is that most lakes rarely freeze solid. This is because the ice and eventually snow act as an insulate to the water below it. This phenomena allows fish and other creatures like zooplanktons to survive the harsh winter. So how do we know if it is safe to go on the ice? We measure the thickness by drilling a whole right into the ice. If the thickness is 4″ or more, we are able to go for a hike.