ABSTRACT
This chapter suggests that meteorological drought should be seen as the initial phenomenon, derived mainly from changes in the global atmospheric characteristics at regional scales, in the sequence of phenomena recognized as various forms of drought. It recognizes four types of drought phenomena that need to be separated out four causes, four sets of criteria which explain the differentiation. The chapter focuses on the four categories that derive from the various effects of the first, meteorological drought, which depends for its mechanisms upon the variations in solar radiation and the 'natural' movements over the surface of the earth. It suggests that meteorological drought occurs when either precipitation is significantly reduced for a significant period of time, or the evaporation or evapo-transpiration of moisture from a land surface, or usually a combination of both, results in a reduction in local soil moisture for long enough to have an adverse impact on the local ecology.
