Abstract
Observed critical wind speeds for the generation of wind waves are compared with those derived from a shear-flow instability theory. The theory predicts that the critical wind speed depends on the fetch and, for the case of infinite fetch, it is 93 cm s−1 at 30 cm above the mean water surface, which agrees well with observations at sufficiently large fetch. For water containing soap, the much larger critical wind speeds which are observed cannot be explained by the reduction of surface tension alone. A qualitative discussion suggests that the elasticity of surface films of soap can effectively increase the critical wind speed.
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Kawai, S. Discussion on the critical wind speed for wind-wave generation on the basis of shear-flow instability theory. Journal of the Oceanographical Society of Japan 35, 179–186 (1979). https://doi.org/10.1007/BF02108637
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DOI: https://doi.org/10.1007/BF02108637