The wind field is a Rankine-type vortex: solid-body rotation inside the core, v = Vmax r / Rc, and a decaying free-vortex outside, v = Vmax (Rc/r)n (n = 1 is the classical irrotational case; smaller n gives a broader wind field). A radial inflow with angle δ is added, vr = -vt tan δ. Seen from the ground, the storm's forward motion adds to the rotation on the right-hand side (counter-clockwise vortex in the northern hemisphere), which is why damage swaths are asymmetric.

The central pressure drop follows cyclostrophic balance, dp/dr = ρ v²/r. Integrated from infinity it gives Δp = ρ Vmax² (1/2 + 1/(2n)), i.e. ρV² for n = 1 (a 100 m/s vortex means about 120 hPa). Real tornadoes are three-dimensional and turbulent, with a suction vortex structure, an updraft and a funnel that this plan-view model does not resolve.

The EF rating uses the Enhanced Fujita 3-second gust thresholds (105, 138, 179, 219, 267 and 322 km/h). In practice EF ratings come from damage surveys, not wind measurements. Colours show the instantaneous gust at ground level in the model, not damage. The time-scale slider speeds up the animation only.