Interfacial Wave Breaking in Stratified Liquids

Experimental results are presented which support the hypothesis that interfacial instability is controlled largely by the difference in density, Δ P, and the thickness of the transition region, δ, between the two layers. The horizontal velocities of the upper and lower layers associated with an internal seiche episode in a stratified lake are examined analytically in relation to critical shear gradients necessary for the growth of unstable short period interfacial waves with frequency close to the Brunt-Vaisala frequency. Experimental results obtained from steady nonuniform surface flows over a stagnant denser fluid are presented which help to clarify the conditions for the occurrence of the short period waves.