2D Tornado — Top-Down Rankine Vortex

Seen from above, this companion to the 3D Tornado simulation replaces decorative spinning with a real Rankine vortex velocity field — solid-body rotation inside the core radius and 1/r irrotational decay outside it — and advects inertial debris particles through that field with genuine Stokes-drag dynamics, so light dust rides the swirl while heavy debris centrifuges outward right at the radius of maximum wind.