Dust Devil Simulator (2D) | mysimulator.uk

Surface Heating

Ground − air ΔT 18 °C

Ambient Wind Shear

Horizontal wind 4.0 m/s

Ground warming — waiting for a vorticity seed.

Live Readout

Updraft w

0.0 m/s

Tangential v_max

0.0 m/s

Core ΔP

0.0 hPa

Rotation period

— s

Core radius

0.0 m

Lofted debris

How it works

A dust devil is a convective vortex: solar heating of the desert floor makes the surface layer buoyant, and it rises as a narrow thermal with velocity scale w ≈ √(g·ΔT/T·H). On its own that thermal has no rotation — the spin has to come from somewhere.

The source is ambient wind shear: a light horizontal wind crossing uneven, bumpy desert terrain generates small pockets of horizontal vorticity, and the rising thermal tilts that spin into the vertical, stretching and concentrating it (vortex stretching conserves angular momentum, so a shrinking radius spins up faster — the same mechanism that tightens a figure skater's spin). Too little wind leaves no vorticity to tilt; too much wind tears the column apart before it can organize, so real dust devils favour a narrow band of light, gusty wind (roughly 2–6 m/s).

Once spun up, the core behaves like a Rankine vortex: solid-body rotation inside the core radius, decaying as 1/r outside it. Cyclostrophic balance (centripetal force balanced purely by the radial pressure gradient, negligible Coriolis at this scale) gives a core pressure deficit of roughly ΔP ≈ ρ·v_max²/2 — the same low-pressure core that lets a real dust devil lift sand, leaves and litter into its rotating dust column.

Dust column — Rankine vortex Lofted debris Ambient wind shear