Schematic illustration of the secondary flow around the eye of a hurricane. The frictional indraft feeds the buoyancy-driven primary updraft and outflow in the eyewall cloud. Saturated convective downdrafts in the eyewall and the evaporatively driven descent along the inner edge of the eyewall feed moist air into the volume below the inversion surface. Dynamically driven descent of dry air inside the eye warms the air column adiabatically. The descent is forced as entrainment into the eyewall draws mass from the bottom of the eye into the eyewall. Balance between moist-air production and loss by entrainment determines the rate of rise or fall of the inversion.