From internal waves to microscale breakers: towards understanding their role in large-scale processes

湖泊、海洋和大气都是密度分层的流体。在湖泊中，层化最常见的原因是温度的变化，冷密的水位于较轻、较温暖的表层水域之下。有时，盐分的存在可能会促进层化。在海洋中，温度和盐度的变化都很重要。层化的一个后果是内部重力波的存在，这种重力波普遍存在于湖泊、海洋和大气的内部。这些波是由作用在垂直位移的流体上的重力恢复力驱动的。在湖泊和海洋的表面，发现了表面水波。在这里，引力恢复力和表面张力都发挥了作用。表面张力显著地改变了长度尺度小于几厘米的表面波的性质。

Lakes, the oceans and the atmosphere are all density stratified fluids. In lakes the stratification is most often due to temperature variations, with cold dense water lying beneath lighter, warm surface waters. Sometimes the presence of salts can contribute to the stratification. In the ocean variations in both temperature and salinity are important. One consequence of the stratification is the presence of internal gravity waves which are ubiquitous in the interior of lakes, oceans and the atmosphere. These waves are driven by gravitational restoring forces acting on vertically displaced fluids. At the surface of lakes and oceans, surface water waves are found. Here gravitational restoring forces as well as surface tension forces come in to play. Surface tension significantly modifies the properties of surface waves at length scales less than a few centimeters.