Sand dunes are primarily formed in arid and semi-arid regions where strong winds blow over loose sand. These areas can include deserts, coastal regions, and riverbanks. The process begins when wind lifts and transports individual sand grains through a process known as saltation, where the grains bounce along the surface.
As the wind loses its energy, it can no longer carry the sand particles, causing them to settle and accumulate. Over time, this accumulation leads to the formation of dunes. The shape and size of these dunes can vary greatly depending on factors such as wind speed, sand supply, and vegetation. Some common types of wind-formed dunes include crescent-shaped barchan dunes and linear dunes, which can create stunning landscapes in places like the Sahara Desert or on the coastlines of beaches.