It occurs throughout low-mass stars and in the outer 30 percent by radius of the Sun where the magnetic field is connected to the associated fluid motions.  
In stars it occurs when entropy increases outward.  Its efficiency is measured by the Nusselt number and it's usually parameterized by a mixing-length theory which treats parcels of buoyant fluid.  It occurs throughout low-mass stars and in the outer 30 percent by radius of the Sun where the magnetic field is connected to the associated fluid motions.  For ten points, name this method of heat transfer.
In stars it occurs when entropy increases outward.  Its efficiency is measured by the Nusselt number and it's usually parameterized by a mixing-length theory which treats parcels of buoyant fluid.  
convection