Observations of the density and velocity structure of the interstellar medium have long suggested that it is turbulent. Characterizing this turbulence presents some unique challenges, as the observations are often averaged along the line of sight and in the plane of the sky, and the gas may be optically thick. Because turbulence has important effects on the structure and dynamics of the interstellar medium, on the dynamo, which sustains the galactic magnetic field, and on the acceleration and propagation of cosmic rays, characterization of interstellar turbulence is of great importance.
Some time ago, a variety of different measurements were combined to argue that interstellar turbulence has a Kolmogorov spectrum. Recent research in CMSO applying novel analysis tools to Ha observations obtained at Wisconsin with the NSF supported WHAM instrument supports this picture.

The "Big Power Law in the Sky" compiled originally by Armstrong, Rickett, & Spangler, with the WHAM measurements shown in the upper left. From A. Chepurnov and A. Lazarian