ZR Relationships So, if we assume a certain drop size distribution (e.g., Marshall Palmer):
then recall: Z = Z(RR, SD) , so now we have a direct relation between Z and RR since SD is known. An empirical relation between Z and R has been found to be: Z = AR^{b} where A and b are empiricallyderived constants. The most common form of this ZR relation is for rain assuming a Marshal Palmer drop size distribution: Z = 200R^{1.6} 
Important Notes:
