A tornado is a rapidly rotating column of air in contact with both a cumulonimbus cloud and the ground. The simulation models the converging updraft: surface inflow spirals inward (conservation of angular momentum), accelerates upward through the funnel, and is carried away aloft. Pressure drops to 100 mbar below ambient near the core.
Click anywhere to seed the initial vortex. Use the wind speed slider to control inflow intensity and the rotation slider for angular momentum. The humidity control affects condensation funnel visibility. Watch particles trace helical paths — inner ones spiral tightly, outer ones describe broad arcs.
The most destructive tornadoes (EF5) have wind speeds exceeding 320 km/h. The Fujita scale, developed in 1971, rates damage from EF0 (minor) to EF5 (incredible). The United States averages ~1,200 tornadoes per year — more than any other country — concentrated in "Tornado Alley" where dry polar air meets warm Gulf moisture.
This simulation models a tornado as a helical vortex: thousands of particles spiral inward and upward through a funnel whose radius narrows with height following a power-law profile. Each particle's angular velocity rises near the core (conservation of angular momentum) and falls toward the edge, while a turbulent radial term and an oscillating wind offset push the funnel sideways. You see a depth-sorted particle field, a translucent funnel silhouette, and a ground dust ring that together approximate the converging-updraft structure of a real twister.
Tornadoes are rapidly rotating columns of air connecting a cumulonimbus cloud to the ground, driven by a rotating mesocyclone within a supercell thunderstorm. The pressure deficit near the core can exceed 100 mbar, and the most violent EF5 events carry winds over 480 km/h. The same fluid-dynamics principles — vorticity stretching, pressure-gradient inflow, and angular-momentum conservation — underpin weather forecasting, wind-engineering of buildings, and the design of cyclone separators in industry.
What does this tornado simulation actually show?
It shows thousands of particles tracing helical paths inside a vortex funnel. Particles spiral faster near the core and slower at the edge, drift upward, and are recycled at the top, approximating the converging, rotating updraft of a real tornado.
Why do the inner particles spin faster than the outer ones?
Because angular momentum is conserved: as air spirals inward to a smaller radius, its rotational speed must increase. The simulation models this with an angular velocity that scales inversely with radial distance from the core.
Is this a physically exact Navier–Stokes solver?
No. It is a simplified, Navier–Stokes-inspired particle model that captures the qualitative vortex behaviour — helical inflow, narrowing funnel and wind drift — without solving the full fluid equations, so it stays fast and interactive in the browser.
Intensity scales the angular velocity (rotation rate), Width scales the funnel's base and top radii, and Wind sets the horizontal drift that makes the funnel lean and wander across the screen. Speed scales the overall time step.
Dust & Dirt tints particles brown, Rain & Hail tints them blue, and Fire & Smoke tints them orange-red. They only change particle colour and opacity to suggest what the vortex is lifting; the motion is identical.
By the Enhanced Fujita (EF) scale, from EF0 (winds ~105–137 km/h) to EF5 (over 320 km/h). The rating is assigned from observed damage rather than measured wind, since direct measurement inside a tornado is rare and dangerous.
The strongest measured tornado winds, recorded by Doppler radar near Bridge Creek–Moore, Oklahoma in 1999, reached roughly 484 km/h (about 301 mph), among the highest wind speeds ever observed on Earth.
The visible condensation funnel forms when the pressure drop in the core cools the air below its dew point, condensing water vapour into cloud droplets. Dust and debris lifted from the surface make the lower part visible too.
Yes. Click and drag on the canvas to reposition the vortex centre, mimicking how a real tornado tracks across the landscape as its parent storm moves.
The United States records the most, around 1,200 per year, concentrated in "Tornado Alley" where warm, moist Gulf air collides with cool, dry continental air to spawn the supercells that breed tornadoes.