Radiowave scattering observations of turbulence in the solar wind and the interstellar medium

Turbulence in a plasma medium produces random fluctuations in the amplitude and phase of a radio wave which propagates through that medium. These amplitude and phase fluctuations can produce blurring of images, temporal and spatial fluctuations in the intensity of the received radiation, broadening of a monochromatic radio signal, and other effects. All or most of these phenomena are observed for radio waves which have propagated through the solar corona, the interplanetary medium, and the interstellar medium, and are the basis of much of what we know about turbulence in these media. It is remarkable that media as different as the solar corona and the Diffuse Ionized Gas component of the interstellar medium can be probed with the same radio telescopes, such as the Very Large Array and Very Long Baseline Array of the National Radio Astronomy Observatory, in the same range of radio frequencies. I summarize what these measurements tell us about the turbulence and its host plasma in the corona and other astrophysical plasmas. I concentrate on studies of shock waves in the interplanetary medium, which can be studied by both in-situ and radio propagation measurements, and discuss what these results imply for supernova remnants, which can only be studied by radio propagation techniques.