Geoscience Principle Animation:Typhoon Structure and Landfall Lab

Above 26.5 °C the sea evaporates enough for rising, condensing vapour to keep heating the air; the inflow is deflected by the Coriolis force and twisted into a vortex. Try dragging the sea temperature below 26.5 °C.

Low-level air spirals inward and is forced up in the eyewall—the tallest clouds, strongest wind and heaviest rain. Some air sinks and warms in the eye, so it is calm and mostly clear. The warm, light column is why central pressure is lowest.

Pressure keeps falling toward the centre, but wind peaks at the radius of maximum wind and drops inside the eye. The storm spins while it moves, so winds add up on the side where spin and motion align—the right of track in the Northern Hemisphere.

Onshore winds pile water onto the shallow shelf and the low central pressure lifts the sea a little more—the coast rises a metre or two or more: a storm surge. Over land the storm loses its warm-sea fuel and meets more friction, so the wind drops within hours; the faster it moves, the farther strong winds reach inland.