Polymictic lakes are holomictic lakes that are too shallow to develop thermal stratification; thus, their waters can mix from top to bottom throughout the ice-free period.
Polymictic lakes can be divided into cold polymictic lakes (i.e., those that are ice-covered in winter), and warm polymictic lakes (i.e., polymictic lakes in regions where ice-cover does not develop in winter).
[1] While such lakes are well-mixed on average, during low-wind periods, weak and ephemeral stratification can often develop.
This article about geography terminology is a stub.
You can help Wikipedia by expanding it.