How do barchan dunes get their crescent shape?
Quick Answer
Barchan dunes form where sand is limited and wind blows mostly from one direction. Their horns point downwind as sand moves around the edges faster than over the center.
The Full Story
Barchan dunes are crescent-shaped dunes with gentle windward slopes and steep slip faces on the downwind side. They typically form in deserts with a firm surface, sparse vegetation, and a steady one-directional wind. Because sand moves more quickly around the dune’s sides than across the middle, the horns extend downwind. These dunes can migrate surprisingly fast compared with other dune types. Barchans are common in places such as the Taklamakan, the Sahara, and parts of the Namib Desert.
Key Facts
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