FALL OVERTURN

A physical phenomenon that may take place in a body of water during early autumn. The sequence of events leading to fall overturn include: (1) The cooling of surface waters; (2) A density change in surface waters producing convection currents from top to bottom; (3) The circulation of the total water volume by wind action; and (4) Eventual vertical temperature equality. The overturn results in a uniformity of the physical and chemical properties of the entire water body. Also referred to as Fall Turnover. Also see Spring Overturn.