Use of a lognormal distribution of raindrop sizes in millimetric radio attenuation studies

Several attempts (Laws and Parson, 1943; Marshall and Palmer, 1948; Joss et al., 1968; and Deirmendjian, 1963) made to characterize drop-size distributions by simple mathematical functions are briefly discussed. Evidence is given to support the existence of a lognormal distribution of drop sizes near ground level. Consideration is given to theoretical evidence, direct experimental evidence, and indirect experimental evidence. Attenuation coefficients are presented for vertical and horizontal polarization, frequencies in the range of 11 to 40 GHz, and uniform rain rates in the range of 1.25 to 100 mm/h.