Internal gravity waves in the neutral air propagating through the ionosphere cause a corresponding disturbance in the ionization. This note discusses additional effects that arise owing to the presence of an electrostatic field and background wind and in particular the possibility of a ‘spatial resonance’ when the natural drift of ionization irregularities equals the phase velocity of the gravity wave. The electrostatic field may be the one associated with the tidal motions that drive the Sq current system. It is shown that short-period (τ<30 min) disturbances in the F region may be appreciably affected by spatial resonance, if the component of E×B/B2 drift in the wave normal direction is equal to the phase velocity of the wave. In the E region a similar coincidence between the ion drift velocity and the wave phase velocity may cause intense patches of sporadic E to drift almost with the background wind at the sporadic E height.