Temperature variation and thermal stratification of Lakes

Temperature variation and thermal stratification:

The body of water has a high density where the deep water is less mixed. As temperature varies, as the difference between water layers becomes pronounced. The change in the temperature at different depth results in water layers, namely; epilimnion, metalimnion, and hypolimnion. 

The high density of water body in the lake the colder the water, this means during summer the bottom water layer (hypolimnion) is the densest layer. The water circulates in epilimnion layer separately from hypolimnion layer, while the whole water body circulation happens either in two seasons or more in deep lakes, the below table shows the different types of water circulation and the type of lakes according to the duration of water circulation.  

Table 1. The types of lakes according to extend of water circulation

Lakes type according to water circulation	Water circulation
Meres	Very shallow lakes the considered to contain only epilimnion layer.
Dimictic	Water circulation happens during spring and fall
Meromictic	Very slow water circulation results in the formation of thermal bar between the water upper layer and bottom of the lake.

From the above table it can be seen that shallow lakes where water body circulates easily, the water is well mixed. The other two types; dimictic and meromictic, the water mixing of the lakes take time, which creates thermal boundaries between the layers of the lake.