How a Sand Dune Forms Sand dunes form wherever there’s constant wind and sand. The size of
a dune depends on how much sand there is in an area. The shape of a dune depends on the direction and force of the wind.
BARCHAN DUNES “Barchan” is the Turkish word for “crescent- shaped.” This type of dune is found on the edges of sand seas. It’s formed when the wind blows steadily in one direction.
crest
windward side
leeward side
Direction of wind
SEIF DUNES Long rows of sand are named after the Arabic word for “sword.” These form in parts of the Sahara where there is a moderate amount of sand and shifting winds.
Direction of wind
STAR DUNE Star-shaped dunes form in areas with a lot of sand and seasonally changing winds.
Direction of wind 21
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