Radio Attenuation at 11 kmc and Some Implications Affecting Relay System Engineering

73 74 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1 9 5 9 R A I N F A L L RATE IN INCHES PER HOUR Fig. 1 -- Rain attenuation vs. rainfall rate (theoretical, after Ryde and Ryde ). 1 * The Bentley method involves exposing trays of sifted flour to the rainfall, baking the Hour to solidify the pellets formed by impinging raindrops and then sorting the pellets by size. The flour has been calibrated by generating drops of known size, so that drop size can be determined from the pellet size. t It is interesting to note that, from his computations, Ryde concludes that the excess attenuation caused by hail is in the order of one-hundredth that caused by rain, that ice crystal clouds cause no sensible excess attenuation, and that snow produces very small attenuation, even at the excessive rate of fall of five inches per hour.