The Oceanic and Atmospheric Boundary Layers Under Windy Conditions

Abstract

Even a cursory observation of the sea surface when a fresh breeze is blowing shows that the appearance of spray in the air is associated with the breaking of the steep crests of wind waves. However, from this essentially trivial conclusion we still have a long way to go before we understand how the droplets become separated from the water surface. This process, which is utilized in a number of engineering devices and which in applied science is called ‘entrainment’, has been investigated repeatedly in the laboratory, by passing an air flow over a film or thin layer of liquid (Kutateladze and Styrikovich, 1976; Soo, 1969; Wallis, 1969). Although the main purpose of these studies was to obtain empirical relationships in order to solve purely applied problems, still the physical processes governing entrainment were investigated at the same time. A process which is considerably more complex and which has been investigated much less is the generation of spray at the sea surface in a high wind; this process has been the subject of only a few laboratory (Toba, 1962) and field (Monahan, 1968) experiments.