An internal wave travelling up the Derwent River estuary in Hobart, Tasmania. The effect of the wave is visible by streaks of smooth water produced by the convergences above the wave troughs (compare Figure 10.7).The wave seen here is of the shortest possible wavelength (compare the distance between the streaks with the yacht) and has a period of 10 - 20 minutes. The estuary stretches from left to right. Note how the shape of the streaks reflects the faster propagation speed of the internal wave over deeper water (in the central channel of the estuary).

The photograph was taken at the CSIRO Marine Laboratories.

© 1996 by M.Tomczak, courtesy of R. Smith, Oregon State University

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