Effects of Adverse Weather on Free Space Optics

The transmission of optical waves through the atmosphere can be severely hampered by adverse weather. This chapter is a state-of-the-art assessment of the models quantifying laser beam attenuation by fog and hydrometeors. The approach used here is, first, to set-up a microphysical model of the interaction between an optical wave and the atmospheric particles, which works as a benchmark. Then, a number of empirical formulas used in the engineering practice are validated against the model. The former are based on simple relations between attenuation and easily-accessible quantities, such as the visibility or the precipitation rate.