Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Contributors
- Frequently Used Symbols
- 1 Overview
- PART 1
- PART 2
- 8 The Influence of Swell on the Drag
- 9 The Influence of Unsteadiness
- 10 The Dependence on Wave Age
- 11 The Influence of Mesoscale Atmospheric Processes
- 12 Wind, Stress and Wave Directions
- 13 The Influence of Surface Tension
- 14 The Influence of Spatial Inhomogeneity: Fronts and Current Boundaries
- 15 Basin Boundaries
- References
- Index
13 - The Influence of Surface Tension
Published online by Cambridge University Press: 16 October 2009
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Contributors
- Frequently Used Symbols
- 1 Overview
- PART 1
- PART 2
- 8 The Influence of Swell on the Drag
- 9 The Influence of Unsteadiness
- 10 The Dependence on Wave Age
- 11 The Influence of Mesoscale Atmospheric Processes
- 12 Wind, Stress and Wave Directions
- 13 The Influence of Surface Tension
- 14 The Influence of Spatial Inhomogeneity: Fronts and Current Boundaries
- 15 Basin Boundaries
- References
- Index
Summary
Introduction
Before addressing the issues of the effects of surface tension on drag over the ocean, it is necessary to describe the physical properties and their controlling influences that make surface tension important to the air–sea boundary conditions. Surface tension is a special case of interfacial tension, that is, the pull between the molecules at the interface between two immiscible fluids. This pull exists because the molecules in the interfacial layer have fewer nearest neighbouring molecules of their own kind than do molecules in the bulk phase of either fluid. It is a physical quantity important to air–sea interaction because it affects many hydrodynamic phenomena, most notably, capillary and capillary–gravity waves. The single most important reason that these short waves (having wavelengths between about 0.1 to 30 cm) are influenced by surface tension is not really directly due to surface tension, but to surface elasticity, which is caused by the lowering of surface tension introduced by the addition of surfactants. Surfactant is a term coined by F. D. Snell that is short for surface-active agent. It describes molecular species that are more thermodynamically favoured to reside at the surface of a liquid. Typically, molecules that act as surfactants in aqueous solutions have two moieties, one hydrophilic (water-liking) and one hydrophobic (water-avoiding). In both terrestrial and aquatic environments that contain biological organisms, molecules composed of two such moieties are common.
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- Chapter
- Information
- Wind Stress over the Ocean , pp. 242 - 253Publisher: Cambridge University PressPrint publication year: 2001