What do we know about the temperature of lake water?

See the ice pushing up on the shoreline!

I became curious, watching the men try to rescue their fishing huts on Big Rideau.

Due to the density-temperature relationships lake water temperatures tend to stratify and separate into distinct layers.

Understanding Lake Ecology
Density Stratification

In the spring, immediately after ice-out in temperate climates, the water column is cold and nearly isothermal with depth. The intense sunlight of spring is absorbed in the water column, which also heats up as the average  daily temperature of the air increases.

Living beside a small lake, as we did from 2006 - 2010, and cottaging there for 50 years, I began to get curious about lakes. We had much Lake Effect Snow, and rain.

The Great Lakes don't freeze over as do smaller bodies of water. Lakes stay at a pretty constant at 4˚ C. on the bottom during winter.

Here you can see the meltwater on the top.
Once the ice warms up, it will sink, melt, and disappear.

It settles in layers by temperature.

Summer lake water varies in temperature
as the wind mixes it up.

The wind mixes the layers, whether there is ice there or not. I once heard a truck cross the ice, they were racing up and down. You could hear the lake water underneath sloshing on the shorelines. It made me curious!

You can see the ice on the top of the lakes. Underneath a demon lurks in the constant temperatures deep below the surface (4 C.).

Lake Effect Snow
The prevailing winds pick up the moisture from the open Great Lakes water, and dump it all over those of us to the east of Georgian Bay. The same is true of those parts south and east of the Great Lakes. You can check out the surface temperatures there.

The Great Lakes

Our Great Lakes have a monomictic mixing regime.  That is they mix fully once per year and are mixed winter and spring.

Lake Maximum Depth and Area 

Lake Huron

228m

14.8 x 106 acres (6.0 x 106 ha)

Lake Ontario

244m

4.9 x 106 acres (2.0 x 106 ha)

Lake Michigan

281m

14.4 x 106 acres (5.8 x 106 ha)

Lake Erie

70m

6.4 x 106 acres (2.6 x 106 ha)

Lake Superior

300m

20.3 x 106 acres (8.2 x106 ha)

Water differs from most other compounds because it is less dense as a solid than as a liquid. Consequently, ice floats, while water at temperatures just above freezing sinks. As most compounds change from a liquid to a solid, the molecules become more tightly packed and is more denser as a solid than as a liquid. Water, in contrast, is most dense at 4°C and becomes less dense at both higher and lower temperatures. 

Puddles in the ditch from Jennifer Jilks .
Puddles in the ditch from Jennifer Jilks on Vimeo.

Doing some research on lake water, I noticed that our ditch puddle was simulating the lakes. The wind blows on the ice surface, which succumbs to the pressure, and ebbs and flows like a tidewater.

Spring

In lakes of the upper Midwest and at higher elevations, the water near a lake’s bottom will usually be at 4°C just before the lake´s ice cover melts in the spring. Water above that layer will be cooler, approaching 0°C just under the ice.

Heads up - it's rolling in

We watch the sky a lot, when we're not checking weather reports.
 Sometimes the best predictor is looking out the front door over the horizon!

Note the melting lake water. The temperatures have been less that that to keep the lake frozen. Water is most dense at 4°C and becomes less dense at both higher and lower temperatures. It is an anomaly in the world of compounds.

Ice floats and water, at temperatures just above freezing, sinks. Water is nearly isothermal with depth. Down in the depths of a lake the temperature is constant. Without any wind, this would be even more true. But both water density and wind mix and modify the lake. This is why sky watching involves watching the lake, too!

Due to the density-temperature relationships lake water temperatures tend to stratify and separate into distinct layers. You can see the meltwater on the top of the lake. Underneath a demon lurks in the constant temperatures deep below the surface. With the wind, it mixes the layers, whether there is ice or not.

You can see the weather moving in! It brings winds and the moisture whipped up from Georgian Bay to be dropped on those near the Great Lakes basin. This water cycle fascinates me. 

Evaporation, condensation, precipitation, respiration.
The interaction of photosynthesis and respiration by plants, animals, and microorganisms characterize the food web. We are all connected.
These organisms are all part of a food chain or web . A food chain is a linear connection between one organism and another relying on one another to survive. A food web is an interconnected web that illustrates the many connections between organisms.


I am fascinated with watching both the sky and the lake. And then a gorgeous sunset. What a blessing.

The wind on the ice surface causes the ice to flex and bow. It is most magical, especially when the shoreline is melted and the center of the lake is still frozen. The water rushes up and down like the tides at the shoreline. It is like the mother's hand that rocks the cradle, gently soothing the soul.


This is the water at the Bala falls on a slow day in winter! Check out my YouTube video for the sound! It is a powerful force, adding to the sensory experience of Muskoka.


Other effects on the lake, include water levels. In many lakes, especially in Muskoka with a complex web of streams, brooks, rivulets, creeks, ox-bow rivers all leading to a larger river or Georgian Bay.
Our lake has frozen, but it is not unmoving. The lake level changes regularly.

The Moon River, a massive transportation system for people and logging in the early development of Muskoka, was used by tribes 7,000 years ago.

Reflections on water

The staff of life...
There must be a poem in here somewhere!

Too bad I have to scrape & sand paint in order to repaint the cottage, in preparation for repairs and some new eavestrophe. This is so much more fun!


If I were gainfully employed I'd be able to hire 'peeps'!
OK, back to work.