- News Home
17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
- About Us
Video: Grains Shape the Songs of Sand Dunes
25 October 2012 5:12 pm
When plagued by whipping desert winds, sand dunes signal their displeasure with haunting moans that reverberate across the arid landscape. Some emit single-note songs while others mimic a jumbled chorus—but no one knew why they sang these different songs until now. New research published online this week in Geophysical Research Letters finds that the size of sand grains shapes a dune's song. Scientists collected sand from a singing dune in Morocco that moans at around 105 hertz (Hz)—or, to a musician, that's G-sharp two octaves below middle C. They compared those grains to sand collected from a dune in Oman, which produces notes ranging from 90 Hz to 150 Hz (F-sharp to D). By creating mini-dune avalanches in the lab, scientists recreated these desert songs, finding that different layers of sand aren't necessary to produce the moans, as previous researchers contended. They also found that when they sieved the Omani sand so that the grains were similarly sized, the resulting "avalanche" produced a single-note song. The synchronized movement of sand grains, they conclude, produces the famed moaning, while grain size determines the notes contained in the song.
See more videos.