Measurement of Rainfall by Radar

Experiments at wavelength 10 cm have verified the theoretical finding that the power obtained from radiation reflected from rain is proportional to Z, the sum of the sixth powers of diameters of raindrops' contained in a representative volume. No value has been obtained for the constant of proportionality. Correlation of Z with, rainfall intensity R (both at ground level) on logarithmic scales shows that, within a factor of about two, Z α R2. Vertical scans of rain storms by radar indicate that variation of rain content with height is moderate and accountable. It may be possible therefore to determine with useful accuracy the intensity of rainfall at a point quite distant (say 100 km) by the radar echo from that point.