Schematic illustration of the secondary flow around the eye of a
hurricane. The eyewall cloud is gray with a blue
frictional indraft feeding the buoyancy-driven, primary updraft and
outflow. The saturated convective downdrafts in
the eyewall are dark green, and the evaporatively driven descent along
the inner edge of the eyewall is brown. Both
downdrafts feed moist air into the volume below the light green inversion
surface. The vertical yellow arrows are
the dynamically driven descent inside the eye, and the horizontal, curved
ones are entrainment into the eyewall.
Balance between moist inflow and loss by entrainment to the eyewall determines the rate of rise
or fall of the inversion surface.