  High-resolution Halpha monitoring of Cyg X-1, HD226868 was carried out during
1996-2002 and the resultant spectra analysed in conjunction with 1.5-12 keV
X-ray monitoring. We demonstrate that the Halpha line-profiles have complex
variability on different timescales, controlled in particular by the orbital
period and the focused wind model of mass loss. We find that long-term
variability of the mass loss by the supergiant and short-term variability due
to clumpy structure of the stellar wind dominate during the low/hard X-ray
state and that X-ray photoionization has a relatively small influence on the
line-profile shape and EW variability. During the high/soft X-ray state and
flaring the effect of photoionization the line-profile and EW of Halpha
increases but is still unable to describe the loose anti-correlation between EW
and the low energy X-ray emission. We propose that variability of the mass loss
by the supergiant can change wind velocities in the Stromgren zone around the
accretion disc of the secondary, leading to an increase in accretion rate
through the disc.
