Dependence of a black targetʹs apparent luminance on fog droplet size distribution

The apparent luminance value that a black object viewed through fog acquires because of the daylight scattered towards the observer by air-borne droplets decreases as the objectʹs size increases. This statement relies on the theory of vision through the atmosphere and agrees with the results of photometric and microphysical measurements taken in evolving fogs in northern Italyʹs Po Valley. As a result, the visual range of a large black object observed through fog can be greater than expected by the theory.