Hurricane Eyewall Dynamics

Cross-section through a tropical cyclone: the eyewall contains maximum winds, the eye is calm and warm, outer rainbands spiral inward

Storm Parameters

CategoryCat 4

Max Wind145 kt

Min Pressure940 hPa

Eye Radius20 km

RMW35 km

Controls

Max Wind Speed: 145 kt

Eye Radius: 20 km

Eyewall Replacement

Eyewall Replacement Cycles (ERC): an outer eyewall contracts, cutting off the inner eyewall's moisture supply. The storm briefly weakens, then intensifies with a larger eye.

Physics

Angular momentum conservation: as air spirals inward, it accelerates (M = v·r = const). Maximum winds occur at the Radius of Maximum Winds (RMW). The warm core aloft (−60°C at 15km) creates the pressure gradient.