Sand ripple

Due to the wind, there can be various shapes of ripple on the dune surface. They usually have long and slow windward slope as well as short and deep leeward slope, which migrate at certain rate towards the leeward direction. The form of the sand ripple (figure 4-14) is influenced by many factors such as the power of wind, the direction of the wind, the size of the grain and tiny terrain. Based on the form of the ridge line, sand ripple can be divided into five types, straight, bent, chain, tubular and crescent. 

Figure 4-14 sand ripple