Drought is a normal, recurrent feature of climate, although it is erroneously considered as a rare and
random event. It differs from aridity, which is restricted to low rainfall regions and is a permanent
feature of climate. Drought should be considered relative to some long-term average conditions of
the balance between precipitation and evapotranspiration (i.e., evaporation + transpiration) in a
particular area. It is also related to the timing ( principal season of occurrence, delays in the start of
the rainy season, occurrence of rains in relation to principal crop growth stages) and the
effectiveness (i.e., rainfall intensity, number of rainfall events) of the rains. However, these are only