When there are perfect conditions for producing sand dunes, steady wind in one direction and just enough sand, a barchan sand dune forms. Barchans have a gentle slope on the wind side and a much steeper slope on the lee side where horns or a notch often forms. The whole dune may appear to move with the wind.
Barchan dunes are formed under specific conditions: consistent wind blowing in one direction and sufficient sand. They have distinct features like a gentle slope on the windward side and a steeper slope on the leeward side, often featuring horns or a notch. The dune's movement is influenced by the wind.