A lower-impact angle results in a longer bombardment shadow behind each ripple crest and hence a longer wavelength. This is a long-winded answer, perhaps, but one I that hope helps others to understand these wonderful patterns in nature. A ripple is simply a small wave, having a period of three seconds or less. Wind velocities of three to 15 kilometers per hour will produce water waves having periods up to three seconds. Most water ripples are much smaller, however, coming from the more common winds that blow at between three and 11 kilometers per hour.
Water waves are fairly easy to understand.
They arise when pressure from the wind starts a pressure hump, which passes on its energy to adjacent water molecules in the direction of the wind. As the wind speed increases, the waves become regular and 'march' along the surface at predictable speeds and with predictable heights. Water waves away from shore become unstable when the wind speed exceeds 1. 3 times the waves' speed. At that point, they begin to get steep and begin to break forward, producing whitecaps. The higher the wind in relation to the wave speed, the steeper the waves get, especially on the downwind side.