Comparing Lake Michigan and Spring Lake.
Dimictic Lakes normally have two mixing periods of mixing, one in the spring and one in the fall. The Dimictic Lake warms in the spring until the entire body of water in uniform both in temperature and density. Where as summer stratification breaks down and the fall overturn occurs. As summer passes by, September is the beginning of cooler nights and shorter days, which leads to less solar heating during the day hours. Because of this the eplimnion (shallow water) becomes colder and denser than the hypolimnion (deep water). (For comparisons in lake temperatures refer too table A) The surface epilimnion begins to sink, causing the development of slight vertical currents called â€œconvection currentsâ€ (lake Matters). As September turns to October and the nights are getting colder and colder than the lakes actual temperature, this will produce a layer of fog over the lake. This will continue until the temperature of the air rises and gets close in range to that of the water. While lakes in the fall â€œoverturnâ€ without wind; that can cause accelerated mixing of the lakes water. The overturn happens when the lakes oxygen, nutrients, and plant life remix thought the lake. While the nights are still getting cooler and the days are getting shorter we reach winter and beginning the stagnation period. This period happens usually in middle to late January, where ice covers the lake and no further mixing can occur. See table C: Seasonal Changes, for comparisons of the seasons and the waters in it.
Mixing occurs in all lakes, even though some lakes go through more mixings than others. Lakes that are shallow in depth (20-30 ft.) donâ€™t stratify very well and will usually mix several times during the year. This is usually caused by strong winds high activity thought the waters. There are also times where there is not enough wind to induce an overturn, therefore, it is not unheard of for a lake to reach uniformity thought with no overturn.