A theoretrical framework for studying supercooling and ice formation in turbulent waters is developed. The basic idea is that the problem can be described by a boundary layer theory in which buoyancy effects become important because of suspended ice crystals. The mathematical model based upon transient Ekman dynamics is formulated and explored. The model is based on the conservation equations for mean momentum, heat energy, salinity, and suspended ice concentration in their one-dimensional form. The turbulent exchange coefficients are calculated with a two-equation model of turbulence. The ice nucleation is assumed to be secondary, which means that ice crystals are assumed to be always present in the water as a result of mass exchange with the atmosphere. In the model the mass exchange is treated as a surface boundary condition for the ice concentration equation. Calculated time histories of temperature and ice concentration for different meteoroligical conditions and different rise velocities are presented and discussed. The results are in good qualitative agreement with field and laboratory measurements. The importance of the strong interaction between the ice formation process and the hydrodynamics of the boundary layer is emphasized.