Vertical water motions in a small ice-covered lake

The use of radioactive tracers in previous studies has demonstrated that appreciable water movement can occur in ice-covered lakes. Mathematical evaluation of these results shows that the vertical component of this motion can be calculated and is between one and three orders of magnitude less than the horizontal component. The over-all pattern of circulation is consistent with convective motion caused by heating from below. Sources of heat in the sediments are considered and evaluated. Because of the organized nature of the circulation observed beneath the ice cover, the validity of classical terminology such as ‘winter stagnation’ and ‘dimixis’ is questioned.