Tornadoes form when warm, moist air rises rapidly inside a thunderstorm and encounters conditions that cause rotation and concentration of that rotating air down near the ground. Key stages and concepts

• Instability and rising warm air: The sun heats the surface, causing pockets of warm, buoyant air to rise. If the surrounding atmosphere cools rapidly with height, these updrafts can become very strong, leading to tall thunderstorms (often cumulonimbus clouds).

• Shear and rotation: In environments where wind speed or direction changes with height (wind shear), the rising air can begin to rotate. The spinning motions in the horizontal plane get tilted into the vertical by the strong updrafts, creating a rotating storm core called a mesocyclone in many cases (typical of supercell thunderstorms).

• Formation within a supercell: A persistent, deep rotating thunderstorm (supercell) develops a rear-flank downdraft and organizes its rotation so that warm, moist air is drawn into the low-pressure region at the surface. As the mesocyclone lowers, a condensation funnel forms and, when the rotating column reaches the ground, a tornado is born. Dust and debris often make the funnel visible.

• Visibility and dissipation: Tornado visibility is enhanced by condensation funnels and debris. Downdrafts eventually cut off the warm-air inflow, the funnel narrows, and the tornado dissipates, though complex interactions with the storm continue to influence its lifecycle.

Important notes

• Tornadoes most commonly originate from supercells, but they can form in other storm types as well, albeit less frequently or less intensely.

• The exact physical processes involve multi-dimensional fluid dynamics and thermodynamics, and some details remain areas of active research; still, the general sequence described above captures the widely accepted framework for how tornadoes form in many strong thunderstorms.

If you’d like, I can tailor this explanation to a specific region or climate, or add a simple step-by-step diagrammatic palm-sized guide you could use for quick reference.