  We present an analysis of three Chandra High Energy Transmission Gratings
observations of the black hole binary Cyg X-1/HDE 226868 at different orbital
phases. The stellar wind that is powering the accretion in this system is
characterized by temperature and density inhomogeneities including structures,
or "clumps", of colder, more dense material embedded in the photoionized gas.
As these clumps pass our line of sight, absorption dips appear in the light
curve. We characterize the properties of the clumps through spectral changes
during various dip stages. Comparing the silicon and sulfur absorption line
regions (1.6-2.7 keV $\equiv$ 7.7-4.6 {\AA}) in four levels of varying column
depth reveals the presence of lower ionization stages, i.e., colder or denser
material, in the deeper dip phases. The Doppler velocities of the lines are
roughly consistent within each observation, varying with the respective orbital
phase. This is consistent with the picture of a structure that consists of
differently ionized material, in which shells of material facing the black hole
shield the inner and back shells from the ionizing radiation. The variation of
the Doppler velocities compared to a toy model of the stellar wind, however,
does not allow us to pin down an exact location of the clump region in the
system. This result, as well as the asymmetric shape of the observed lines,
point at a picture of a complex wind structure.
