The distance, under daylight conditions, at which the apparent contrast between a specified type of target and its background becomes just equal to the threshold contrast of an observer; to be distinguished from the night visual range. The visual range is a function of the atmospheric extinction coefficient, the albedo and visual angle of the target, and the observer's threshold contrast at the moment of observation. Only in the so-called meteorological range does one have a visibility figure dependent only upon the extinction coefficient. See visual-range formula; Compare visibility.