The pictures illustrate the formation of sand dunes in a natural environment.
Overall, the process involves 3 main stages,primarily driven by the interaction of wind directions and sand particles, patches of wet ground .A key feature of this process is that moisture traps sand particles, permitting them to accumulate to eventually create sand dunes.
At the first stage, sand particles randomly scatter on both dry and wet ground. Then, winds blow these particles across the ground. Once the dry particles are blown on the wet ground, some of them are captured while the remaining dry particles continue to be blown further on the surface. As a result, these initial layers of sand particles help form the bottom of the future sand dunes.
In the next stage, the process of accumulation continues similar to the first stage.Meanwhile, more sand particles are blown into the wet patches, adding onto the existing clusters.Hence, the volume of wet sand increases dramatically, creating a solid and stable base for the dunes.
The process finishes with sand dunes finally taking shape as their height and volume grows significantly. Interestingly, a mixture of wet and dry sand forms the triangular shape of the dunes, resembling an unfinished pyramid design.Noticeably, the main dunes rose larger on the windward side, whereas a smaller secondary dune is gradually created further downwind in a similar form.