In the open ocean, many mechanisms have been suggested as possible mixing agents. The surface shear stress induced by the wind produces a homogeneous well-mixed layer whose lower boundary is transported downward by entrainment. Turbulent mixing can be created in the ocean by surface and internal wave breaking or by tidal forcing. Buoyancy forces act on the largest scales of vertical motion and tend to suppress large scale turbulent eddies.
Viscous forces act on the small scales and determine the size of smallest eddies.
Scales larger than are dominated by buoyancy and cannot overturn. The inertial force is balanced by viscous effects at the Kolmogorov scale, . Another common scale is Thorpe scale, . It is the rms of vertical displacements in reordering the density profile. Weak internal wave motions at high Ri could contribute to the straining of the density profile but would not affect the vertical displacement .