1. A system for measuring atmospheric visibility, comprising: at least two targets having contrasting portions; a video detector that is aligned to detect said contrasting portions of said targets and that generates a signal indicative of contrast levels of said contrasting portions of said target; and a processor that generates a representative contrast number from said contrast levels detected for each target, and that generates a nonlinear curve based on said representative contrast number detected for each target and the distance of each target from said video detector, and that generates a visibility number based on the slope of said exponential equation.