Barchan

Russian naturalist Alexander von Middendorf introduced the term in 1881,[1] working from the occurrence of barchans in Turkestan and in other inland desert regions.

Barchans usually occur as groups of isolated dunes and may form chains that extend across a plain in the direction of the prevailing wind.

Dune collisions[5][6] and changes in wind direction spawn new barchans from the horns of the old ones and govern the size distribution of a given field.

The process appears superficially similar to waves of light, sound, or water that pass directly through each other, but the detailed mechanism is very different.

[8] Barchan dunes have been observed on Mars, where the thin atmosphere produces winds strong enough to move sand and dust.