Clumping, or random density inhomogeneities
Creates a porous wind, potentially with paths having lower
column densities (but other paths higher, if mass is conserved)
Can reduce average optical depth of the wind appreciably only if
individual clumps are optically thick: Then the atomic cross
section in the opacity is replaced by the physical cross section of
the clump
Clumps would therefore have to be quite large
Non-isotropic clumping can have an effect on line profilesÉ