"February 1965." Includes bibliographical references (pages 56-58).

Drought can be considered as a strictly meteorological phenomenon. It can be evaluated as a meteorological anomaly characterized by a prolonged and abnormal moisture deficiency. Not only does this approach avoid many of the complicating biological factors and arbitrary definitions, it enables one to derive a climatic analysis system in which drought severity is dependent on the duration and magnitude of the abnormal moisture deficiency. The objective of this paper is to develop a general methodology for evaluating the meteorological anomaly in terms of an index which permits time and space comparisons of drought severity. The underlying concept of the paper is that the amount of precipitation required for the near-normal operation of the established economy of an area during some stated period is dependent on the average climate of the area and on the prevailing meteorological conditions both during and preceding the month or period in question. A method for computing this required precipitation is demonstrated.