Sliding sand creates a mysterious symphony
N. Vriend/Univ. of Cambridge
It starts as a hum, barely audible above the howl of the winds shimmying between sand dunes. Then it builds. Within seconds, the sound resembles a World War II–era prop plane flying low overhead. But there’s nothing there. “It’s very mystical and eerie,” says Nathalie Vriend, a mechanical engineer and geophysicist at the University of Cambridge.
This resounding roar, called a boom, has intrigued desert explorers for centuries. Yet only recently have scientists demystified the source of booms and softer, shorter-lived burps that emanate from deserts’ sandy slopes. Much of the new insight has come from Vriend. Her extremely hands-on research, which includes sliding down towering dunes, has revealed that tumbling sand induces pressure pulses that course above and below the surface to produce a cacophony of peculiar noises.