In dense hot star winds, the infrared and radio continua are dominated by
free-free opacity and recombination emission line spectra. In the case of a
spherically symmetric outflow that is isothermal and expanding at constant
radial speed, the radiative transfer for the continuum emission from a dense
wind is analytic. Even the emission profile shape for a recombination line can
be derived. Key to these derivations is that the opacity scales with only the
square of the density. These results are well-known. Here an extension of the
derivation is developed that also allows for line blends and the inclusion of
an additional power-law dependence beyond just the density dependence. The
additional power-law is promoted as a representation of a radius dependent
clumping factor. It is shown that differences in the line widths and equivalent
widths of the emission lines depend on the steepness of the clumping power-law.
Assuming relative level populations in LTE in the upper levels of He {\sc ii},
an illustrative application of the model to {\em Spitzer}/IRS spectral data of
the carbon-rich star WR 90 is given.Comment: to appear in Astronomische Nachrichten (astroph submission is a
preprint version