  I develop a detailed empirical model for the chromosphere and wind of 31 Cyg
based on a previously published analysis of IUE spectra from the 1993 eclipse
and on the thermodynamics of how the wind must be driven. I then use this model
to interpret observations of single supergiant stars and to assess the evidence
that their winds are fundamentally different from those of supergiants in the
binary systems. This model naturally predicts a certain level of clumping of
the gas to balance the pressure that drives the wind. It also predicts that
anisotropic turbulence, such as would result from transverse displacements of
Alfven waves directed along radial magnetic flux lines, would not give the
roughly Gaussian profiles of emission lines seen in cool giant stars.
Furthermore, it implies that C II] may not tell us much at all about general
conditions in chromospheres. Finally, I speculate that chaotic magnetic fields,
in dynamical equilibrium with the gas of the wind, are the actual driving
mechanism.
