I think those are the big three. With the first two (heat and wind), it can get really really complicated. Heat can drive surface evaporation, for example, which can raise the density of the overlying water mass. Wind forces can create distinct forms of water circulation (i.e. Langmuir cells, Ekman spirals). In temperate and boreal freshwater systems, the effects of ice are significant as a mixing force.
Although adjacent water masses of different densities will eventually equalize (due to passive diffusion across the "barrier"), it takes a bloody long time. In the deep oceans, for example, water layers have been roughly aged on century scales. Oceanographers refer to these as "old water".
When you hear reference to "permanent thermoclines", this should not be viewed so uh... permanently. Such density layers tend to be fairly uniform, but their precise position in the water column may not be be fixed (particularly in lakes), and they WILL change over time. It's just a stinking really LONG time. Unless some freak mixing agent sneaks in there... like an asteroid impact or giant mutated sea monsters swimming around. Submarine earthquakes or magma venting can do some fun stuff, too.
Hope this helps!
Although adjacent water masses of different densities will eventually equalize (due to passive diffusion across the "barrier"), it takes a bloody long time. In the deep oceans, for example, water layers have been roughly aged on century scales. Oceanographers refer to these as "old water".
When you hear reference to "permanent thermoclines", this should not be viewed so uh... permanently. Such density layers tend to be fairly uniform, but their precise position in the water column may not be be fixed (particularly in lakes), and they WILL change over time. It's just a stinking really LONG time. Unless some freak mixing agent sneaks in there... like an asteroid impact or giant mutated sea monsters swimming around. Submarine earthquakes or magma venting can do some fun stuff, too.
Hope this helps!
