Fig. 2

Structure of the Venus atmosphere showing the ionosphere peaking between 100 and 150 km altitude (with daytime densities exceeding 10⁵ cm⁻³) and the temperature profile with the main cloud layer around 60 km altitude. Possible sites of electro-optical activity are noted—eolian and volcanic discharges near the surface, convective lightning in the cloud layer, and possible transient luminous events like sprites in the mesosphere. The corresponding altitudes of positive indications of lightning are noted at left