Did you know that sand dunes...can sing?

Sand dunes form wherever there’s sand and steady wind to blow it into piles. Deserts cover 20 percent of Earth’s land surface and many have dunes. There are even sand dunes on other planets.

Here on Earth, sand dunes sing in about three dozen known locations. This has baffled explorers since Marco Polo crossed China’s Gobi Desert in the thirteenth century and attributed the loud noises to spirits.

And scientists still don’t understand it completely. But it has to do with the sand itself.

In singing dunes, the sand crystals are well rounded and covered in a silica-water gel coating called desert glaze.

When the sand is hot and very dry, and tumbles down the dune face, the crystals vibrate against one another. This produces tiny sound waves that synchronize with and amplify each other, growing into moans, whines or whistles that can be louder than a lawn mower.

If the sand grains are a uniform size, the dune will produce a pure tone. If the grains are of different sizes, they’ll produce several notes to form a chord. Listen...

(Fade out music and fade in about eight seconds of singing sand recording. Fade out.)

In the U.S., White Sands National Monument has been singing for thousands of years, as documented by native peoples. When you visit, maybe they’ll sing for you.