Atmospheric Vision 0.35 microm less, similarlambda less, similar 14 microm

A unique analytical description of atmospheric vision in the wavelength range from 0.35 microm to 14 microm is presented. The signal-to-noise ratio corresponding to the apparent radiance difference at the observation site is used as the basic physically limiting magnitude. It establishes a general vision formula, Eq. (18). This shows that the contrast, C = (L(1) - L(2))/(L(1) + L(2)), contrast degradation, and a contrast threshold C(min) = 1/tau DeltaQ(T) can be used for the description of photon-noise limited imaging devices, including the influence of path radiance. Koschmieder's theory of atmospheric vision follows as a special case, using a constant contrast threshold for the human eye. Thermal vision in the atmosphere is discussed, together with the relevant magnitudes for the description of photon-noise limited and detector-noise limited imaging devices that are to be described by the apparent radiance difference only. Finally the problem of defining a characteristic length comparable to the meteorological range V(N) is considered, and a wavelengthdependent meteorological range Vlambda together with a standard maximum range for a special device V(s) is proposed.