Effects of the anomalous temperature dependence of water density on surface gravity current

This paper reports experimental results on the propagation of a plane water jet at a temperature above the maximum-density temperature (4$^\circ$C) along the free surface of initially quiescent water at a temperature of about 0$^\circ$C. For comparison, experiments were performed in which the temperatures of the lower and higher layers were more than 4$^\circ$C, other conditions being equal. The experiments revealed a number of new hydrodynamic effects, including peculiar flow instability and a fine structure of the density field at large times.