Drought is a normal, recurrent feature of climate which occurs in virtually all climatic zones, but its characteristics
vary significantly from one region to another. Drought is a temporary aberration; it differs from
aridity, which is restricted to low rainfall regions and is a permanent feature of climate.
Drought originates from a
deficiency of precipitation over an extended period of time, usually a season or more. This
deficiency results in a water shortage for some activity, group, or environmental sector. Drought
should be considered relative to some long-term average condition of balance between precipitation
and evapotranspiration (i.e., evaporation + transpiration) in a particular area, a condition often
perceived as "normal". It is also related to the timing (i.e., 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. Other
climatic factors such as high temperature, high wind, and low relative humidity are often associated
with it in many regions of the world and can significantly aggravate its severity.
Drought should not be viewed as merely a physical phenomenon or natural event. Its impacts on
society result from the interplay between a natural event (less precipitation than expected
resulting from natural climatic variability) and the demand people place on water supply. Human
beings often exacerbate the impact of drought. Recent droughts in both developing and developed
countries and the resulting economic and environmental impacts and personal hardships have
underscored the vulnerability of all societies to this "natural" hazard.
-explanation from the Drought MonitorFor further and expanded information, try the following links:
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