Formation Process
Desert sand dunes form when wind transports loose sand particles and deposits them in sheltered areas or where obstacles interrupt airflow. The process begins with saltation, where wind lifts sand grains that bounce along the surface, dislodging more particles. Dune shape depends on wind direction consistency, sand supply, and local topography. Different wind patterns create various dune types, from crescent-shaped barchans to linear seif dunes.
Internal Structure
Dunes develop distinct internal layers through repeated sand deposition. Windward slopes typically angle at about 10-15 degrees, while leeward slopes maintain a steeper angle around 32-34 degrees (angle of repose). Sand grains sort by size during transport, creating stratification visible in dune cross-sections. This layering records wind direction changes and seasonal variations in sand deposition.
Movement and Stabilization
Dunes migrate in the prevailing wind direction, moving several meters annually in active desert regions. Vegetation can stabilize dunes by trapping sand and binding it with root systems. Human activities affecting sand supply or wind patterns can alter dune movement. Understanding dune dynamics helps manage desert environments and protect infrastructure from encroaching sand.Shutdown123