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Fig. 5.14
Shadow definition of ripple wavelength k. For a given
windspeed, the impact angle a will be roughly constant, and so will the
aspect ratio h/k: over time, ripples may grow in both height and
wavelength. In faster winds (e.g., on Mars), the angle a will be
shallower, and longer wavelength bedforms result. The solid line shows
a saltating particle (note that k is defined in part by the length of the
shadow zone and is related to, but not equal to, the saltation pathlength).
The thin curves show typical 'splashed' particle trajectories
Fig. 5.15
Some of the largest ripples on Earth: the pumice gravel-coated megaripples, Perulla, Argentina. See Milana (2009) and de Silva et al.
(2012) for further discussion of these megaripples. Shan da Silva for scale. Photo J. Zimbelman
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