Collection: Visibility sensors

Three effects limit atmospheric visibility:

• atmospheric: hydrometeors such as precipitation , snowfall or fog or lithometeors such as dust or smoke dampen the light or the contrast
• Air pollution: Aerosols cause additional light attenuation

Atmospheric scattering and absorption reduce the contrast of an object relative to its surroundings. This phenomenon is called light attenuation. The contrast K {\displaystyle K} depends exponentially on the distance s {\displaystyle s} and an absorption coefficient σ {\displaystyle \sigma } away:

K = K 0 ⋅ e − σ ⋅ s {\displaystyle K=K_{0}\cdot e^{-\sigma \cdot s}}

For perception, a minimum contrast of

K = 0 , 02 = ^ 2 % {\displaystyle K=0{,}02\;{\hat {=}} \;2\,\%}

required. Assuming that the initial contrast K 0 {\displaystyle K_{0}} is approximately 1, can be seen directly from the range s {\displaystyle s} on σ {\displaystyle \sigma } be closed:

σ = ln ⁡ ( 50 ) s ≈ 3 , 91 s {\displaystyle \sigma ={\frac {\ln(50)}{s}} \approx {\frac {3{,}91}{s}} }