What is the difference between Meridional Overturning Circulation and Thermohaline Circulation? Is it correct to say: THC is a principle - basically just the fact that colder and/or saltier water sinks because it's denser than warmer or less salty water. And that if some other factor such as, say, a heat source at the bottom, or wind-driven turbulence at the top, is applied, the temperature and/or salt gradients result in circulation. And you could observe THC in a fish tank if everything was controlled and measured just right. MOC is an actual specific phenomenon that we observe in oceans: a particular pattern followed by currents such as the Gulf Stream (and others?) which is driven by wind, THC, heat from the atmosphere, perhaps some other factors. MOC couldn't be observed in a fish tank because it describes currents in actual places - it's not a principle you can demonstrate, as THC is. .......did I get this right?