Atmospheric aerosol acts both to remove the background concentration of natural cluster ions, and to attenuate optical propagation. In turn this has two consequences, the reduction of the air’s electrical conductivity and reduction of the visual range. The common origin of correlated electrical and optical changes allows visual range measurements, made simply and routinely at many meteorological sites, to offer inferences about the local air’s electrical properties which are much more rarely determined. Good visual range is shown to be associated with fair weather atmospheric electrical conditions.