Theory 55/Lake turnover/Onset phase
Mixing Starts on a Density Threshold
The claim
Lake mixing begins when the ratio of wind energy to density difference exceeds a threshold, so a calm autumn delays turnover.
01Mechanism
Wind must overcome buoyancy; the ratio determines whether the water column overturns.
02Prediction
Turnover should track the ratio.
03Refutation
Turnover tracking air temperature would remove wind.