Drought
Glossary
Being familiar with weather terminology will help you know what to expect when weather warnings are issued. The following terms are used frequently in reference to drought.
- Agricultural drought - refers to a situation
where the amount of moisture in the soil no longer meets
the needs of a particular crop.
- Arid - term used for an extemely dry
climate. The degree to which a climate lacks effective, life-promoting
moisture and agriculture is impracticable without irrigation.
- Climate - the composite or generally prevailing
weather conditions of a region, throughout the year, averaged
over a series of years.
- Climatology - the science that deals with
the phenomena of climates or climatic conditions.
-
Crop Moisture Index - In 1968, Palmer developed
the index to assess short-term crop water conditions and needs
across major crop-producing regions. This index is a useful
tool in forecasting short-term drought conditions.
- Dog days - name given to the very
hot summer weather that may persists for four to six weeks
between mid-July through early September in the United States.
In western Europe, this period may exist from the first week
in July to mid-August and is often the period of the greatest
frequency of thunder. Named for Sirius, the Dog Star, which
lies in conjunction with the sun during this period, it was
once believed to intensify the sun's heat during the summer
months.
- Drought -
a deficiency of moisture that results in adverse
impacts on people, animals, or vegetation over a sizeable
area.
-
Ground water - In hydrologic terms, water
within the earth that supplies wells and springs; water in
the zone of saturation where all openings in rocks and soil
are filled, the upper surface of which forms the water table.
- Hydrological drought - occurs when
surface and subsurface water supplies are below normal.
- Hydrology - The scientific study of the waters of
the earth, especially with relation to the effects of precipitation
and evaporation upon the occurrence and character of water
on or below the land surface.
- Irrigation - In hydrologic terms, the controlled
application of water to arable lands to supply water requirements
not satisfied by rainfall.
- Irrigation requirement - In
hydrologic terms, the quantity of water, exclusive
of precipitation, that is required for crop production.
It includes surface evaporation and other economically
unavoidable wastes.
- Meteorological drought - a measure of
departure of precipitation from normal. Due to climatic differences,
what might be considered a drought in one location of the
country may not be a drought in another location.
- Palmer
Drought Severity Index -
(Abbrev. PDSI) - an index used to gage the severity
of drought conditions by using a water balance equation
to track water supply and demand. This index is calculated
weekly by the National Weather Service.
- Precipitation - process where water vapor
condenses in the atmosphere to form water droplets that fall
to the Earth as rain, sleet, snow, hail, etc.
- Socioeconomic drought - refers to the
situation that occurs when physical water shortages begin
to affect people.
- Soil moisture - water contained
in the upper part of the soil mantle. This moisture evaporates
from the soil and is the used and transpired by vegetation.
- Xeriscape™ - quality landscaping that conserves water and protects the environment. The term Xeriscape (pronounced zera-scape) was coined in Colorado in 1981 in response to a prolonged drought. It derives from merging the Greek word "Xeros," meaning "dry," with the word "landscape."