ABSTRACT
This chapter reviews surface tension at the water-air or water-water vapor interface, convection in the liquid water, waves on the water surface, and related subjects. At the surface of an evaporating body of water, measurements of surface tension are in most cases measurements of interfacial tension. In lowering the temperature of the water surface by removing heat, the evaporation process raises the surface tension of the water at the surface above the value corresponding to the bulk water beneath the surface. Water in this potentially unstable state tends to exhibit surface tension-driven natural convection. It is possible to identify certain flow patterns as being induced by a surface tension-driven instability and others as being due to the buoyancy-driven convection. The presence of interfacial waves increases substantially the gas mass transfer coefficient between gas-liquid phases relative to that for a stagnant interface, mainly through the induction or turbulence in the gas boundary layer.
