  Motivated by theoretical, numerical, and observational evidence, we explore
the possibility that the critical transition between sub-Alfv\'enic flow and
super-Alfv\'enic flow in the solar atmosphere takes place in fragmented and
disconnected subvolumes within a general Alfv\'en critical zone. The initial
observations of sub-Alfv\'enic periods by Parker Solar Probe near
\(16~R_\odot\) do not yet provide sufficient evidence to distinguish this
possibility from that of a folded surface that separates simply-connected
regions. Subsequent orbits may well enable such a distinction, but here we use
a global magnetohydrodynamic model of the solar wind, coupled to a turbulence
transport model, to generate possible realizations of such an Alfv\'en critical
zone. Understanding this transition will inform theories of coronal heating,
solar wind origin, solar angular momentum loss, and related physical processes
in stellar winds beyond the Sun.
