  Warm absorbers and related phenomena are one of the observable manifestations
of outflows or winds from active galactic nuclei (AGN). Warm absorbers are
common in low luminosity AGN, they have been extensively studied
observationally, and are well described by simple phenomenological models.
However, major open questions remain: What is the driving mechanism? What is
the density and geometrical distribution? How much associated fully ionized gas
is there? What is the relation to the quasi-relativistic 'ultrafast outflows'
(UFOs)? In this paper we present synthetic spectra for the observable
properties of warm absorber flows and associated quantities. We use ab initio
dynamical models, i.e. solutions of the equations of motion for gas in finite
difference form. The models employ various plausible assumptions for the origin
of the warm absorber gas and the physical mechanisms affecting its motion. The
synthetic spectra are presented as an observational test of these models. In
this way we explore various scenarios for warm absorber dynamics. We show that
observed spectra place certain requirements on the geometrical distribution of
the warm absorber gas, and that not all dynamical scenarios are equally
successful at producing spectra similar to what is observed.
