This paper describes a series of experiments performed in turbulent and quasi-laminar wind tunnel flows to further assess unipolarly ionised air as a tracer for examining the microstructure of diffusion plumes and puffs. The experimental techniques have been improved which, together with spectral and qualitative correlation analysis, have facilitated a more penetrating examination of ion plume/puff behaviour. Some new insights into the electrostatic aspects of ionised air dispersion have also beeen gained.