Letter to the Editor
An analogy to the Reynolds number for the neutral gas component of a weak plasma

Abstract. The Reynolds number Re is used as a metric to assess whether or not a flow may contain turbulence. In a weakly ionised gas with an external electric field imposed, ions exert a drag on the neutral particles. Thus, a component of the neutral motion is attributable to the ion-drag. An analogy to Re has been proposed in which the ion-drag-induced velocity contribution to the neutral motion is used. This analogy thus represents the destabilising effect of the electric field on the neutral dynamics. Here quantisation of this proposed metric is investigated.

Key words. Meteorology and atmospheric dynamics (turbulence) – Ionosphere (ionosphere-atmosphere interactions; electric fields and currents)