Science Friday The Shape-Shifting Science Of Sand Dunes
Sep 2, 2025
Nathalie Vriend, an associate professor in mechanical engineering at the University of Colorado, studies the fascinating world of sand dunes. She shares how sand dunes transition between solid and fluid states, revealing their unique physical properties. The podcast also explores the enchanting phenomenon of singing sand dunes and the scientific principles behind their sounds. Additionally, Vriend addresses the challenges posed by mobile dunes to nearby communities and discusses innovative methods like satellite tracking used to study these dynamic geological structures.
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Dune As A Scaled-Up Sand Pile
- A dune is a scaled-up sand pile shaped by gravity and wind, with a steep avalanching side and a gentler windward slope.
- Wind asymmetry and size transform a simple heap into the varied dune shapes seen on beaches and in deserts.
Wind And Sand Control Dune Shapes
- Dune shapes depend mainly on sand availability and wind regime, producing distinct patterns visible from satellites.
- Constant unidirectional wind yields uniform migrating dunes while variable winds create complex forms.
Sand Is A Size, Not A Single Material
- 'Sand' denotes a grain size category between clay and gravel, not a single chemical substance.
- Most sands are quartz or feldspar, but some dunes (e.g., White Sands) are gypsum and look and feel very different.