The observation that the ‘clouds’ of galactic neutral hydrogen (0.0001 degree of ionization) are actually filamentary in high resolution radiotelescope data led to the discovery that the linewidths of the atomic species in the presence of the self-field of the current-conducting filaments (Birkeland Currents) fall precisely where predicted by the CIV effect.

The figure shows a histogram of the HI emission linewidths of the Leiden-Dwingeloo 1996 Survey (black bars).

The colored bars represent CIV data tabulated in Physics of the Plasma Universe, A. L. Peratt, Springer-Verlag, 1992.

Critical Ionization Velocity/Neutral Hydrogen Cloud data