  The nature of turbulence in the warm ionized component of the interstellar
medium (WIM) can be investigated using Fabry-Perot spectroscopy of optical
emission lines. The H-alpha intensity provides the emission measure (EM) along
a line of sight, which is used in conjunction with the scattering measure,
rotation measure, and dispersion measure to study interstellar turbulence.
Observations at high spectral resolution (10 km/s) allow measurements of the
bulk radial velocity structure of the emitting gas and investigations of
thermal and non-thermal (turbulent) broadening mechanisms through the line
widths. By measuring the widths of the H-alpha line and an emission line from a
heavier atom (e.g. the [S II] 6716 line), one can separate the thermal and
non-thermal contributions to the line width. Preliminary studies using this
method have shown that the broad range of H-alpha line widths (typically 15 -
50 km/s) is mostly due to differences in the non-thermal component of the width
and that along many lines of sight this component dominates. The Wisconsin
H-Alpha Mapper (WHAM) is in the process of producing a very sensitive kinematic
map of the northern sky in H-alpha at one degree angular resolution and 12 km/s
spectral resolution. WHAM is also mapping emission lines from heavier atoms
such as sulfur and nitrogen for selected regions of the sky. This data set will
provide unique new information concerning turbulence in the WIM.
