In this work we describe interactions between turbulence and water-air surface in the ensemble-averaged picture where, instead of a sharp interface between the phases we deal with a “surface layer” where the probability of the surface position is nonzero. Changes of the turbulent kinetic energy and the characteristic size eddies influence the width of the “surface layer”. We present a numerical solution and convergence tests for the equation for the intermittency function α which describes the probability of finding the water phase at a given point and time.