How are star dunes formed in deserts?

Star dunes are created in deserts with complex wind regimes, where strong winds come from at least two or three different directions during the year. Instead of migrating in one direction like many dunes, star dunes build upward as sand is deposited on several sides, producing a shape with radiating arms. Some of the tallest dunes in the world, including those in the Badain Jaran Desert in China, are star dunes that can rise to more than 250 meters. Their height reflects a long-term balance between sand supply and shifting winds. Because they grow vertically, star dunes can become some of the desert’s largest sand mountains.