  Black hole binaries show equatorial disc winds at high luminosities, which
apparently disappear during the spectral transition to the low/hard state. This
is also where the radio jet appears, motivating speculation that both wind and
jet are driven by different configurations of the same magnetic field. However,
these systems must also have thermal winds, as the outer disc is clearly
irradiated.We develop a predictive model of the absorption features from
thermal winds, based on pioneering work of Begelman et al 1983. We couple this
to a realistic model of the irradiating spectrum as a function of luminosity to
predict the entire wind evolution during outbursts. We show that the column
density of the thermal wind scales roughly with luminosity, and does not shut
off at the spectral transition, though its visibility will be affected by the
abrupt change in ionising spectrum. We re-analyse the data from H1743-322 which
most constrains the difference in wind across the spectral transition and show
that these are consistent with the thermal wind models.We include simple
corrections for radiation pressure, which allows stronger winds to be launched
from smaller radii. These winds become optically thick around Eddington, which
may even explain the exceptional wind seen in one observation of GRO J1655-40.
These data can instead be fit by magnetic wind models, but similar winds are
not seen in this or other systems at similar luminosities. Hence we conclude
that the majority (perhaps all) current data can be explained by thermal or
thermal-radiative winds.
