🏜️ Singing Sand Dune: Wind Threshold, Avalanche Tone and Dry-Layer Resonance (2D cross-section)

Cross-section of a booming dune. Set wind speed, grain size, moisture and the thickness of the dry sand layer, and see whether the wind lifts the sand, which tone the avalanche on the lee face makes, and whether that tone matches a resonance of the dry layer so the dune sings. The 3D cathedral has wind, grain and moisture sliders; this page gives them real units, with four in-page numerical checks.