The phenomenon of singing sand dunes in the Chinese desert

The sand dunes scattered in the Kumtag Desert in Dunhuang city make a distinctive sound when the wind blows through them.

Singing Sand Dunes in Dunhuang City. Photo: Lonely Planet — Singing Sand Dunes in Dunhuang City. Photo: *Lonely Planet*

The singing dunes vary in size, with the tallest reaching 1,715 meters. Up close, they even have rich colors, from yellow and white to green and black. While not unique to Dunhuang, the singing dunes in this region lie along the Silk Road, a vital trade route between Central Asia and Europe for 1,500 years, beginning in the 2nd century BC.

The quality of the sand grains is just one of the factors that make a sand dune sing. Composed of a variety of fine to medium sized grains, the size of the grains allows them to move and interact better. Combined with their shape, this creates a different resonance and frequency. Rounder and smoother grains produce a better sound. The shape of the dune also contributes to the sound. The slope of the dune affects how well the grains interact. Additionally, the right wind conditions are needed to blow the grains enough to produce sound. In strong winds, dunes produce a loud rumble, but in light winds, the sound is more melodious.

The surrounding structure also contributes to the generation and amplification of sound, as hills create air currents that concentrate the wind in specific areas around the dune. When the wind blows the sand grains, friction occurs, causing the sand to vibrate, creating sound. Air pockets between the sand grains can act as resonators, amplifying the sound. Arid climates are another factor in sound production. This is why singing dunes are found in desert environments. Low humidity increases the friction between the sand grains, creating sound as they rub against each other. The combination of sand grain vibration, resonance, and air pockets results in the characteristic sound of a dune.

In addition to Dunhuang, singing dunes have been found in Inner Mongolia, Xinjiang, Gansu, and Ningxia. Similar dunes are found in Namibia’s Namib Desert and California’s Mojave Desert. Researchers regularly monitor the dunes for signs of erosion and traffic. Despite the large number of tourists, the desert winds blow through each night, erasing all footprints, leaving the dunes in their original state.

An Khang (by IFL Science )

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