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An aridity index (AI) is a numerical indicator of the degree of dryness of the climate at a given location. The American Meteorological Society defined it in meteorology and climatology, as "the degree to which a climate lacks effective, life-promoting moisture".
Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, ...
The Gaussen Index (or Bagnouls-Gaussen Index) or xerothermic index is a method of calculating and comparing aridity. According to Henri Gaussen (French botanist and biogeographer ), a given period is said to be arid, when: P < 2 × T {\displaystyle P<{2\times T}} .
There is a significantly greater proportion of drylands in developing countries (72%), and the proportion increases with aridity: almost 100% of all hyper-arid lands are in the developing world. Nevertheless, the United States , Australia , and several countries in Southern Europe also contain significant dryland areas.
The Atacama Desert (Spanish: Desierto de Atacama) is a desert plateau located on the Pacific coast of South America, in the north of Chile.Stretching over a 1,600-kilometre-long (1,000-mile) strip of land west of the Andes Mountains, it covers an area of 105,000 km 2 (41,000 sq mi), [2] which increases to 128,000 km 2 (49,000 sq mi) if the barren lower slopes of the Andes are included.
A phase of intense aridity around 2200 BC is recorded across North Africa, [16] the Middle East, [17] the Red Sea, [18] the Arabian Peninsula, [19] the Indian subcontinent, [6] and midcontinental North America. [20] Glaciers throughout the mountain ranges of western Canada advanced around that time. [21] Iceland also experienced glacial advance ...
The ratio, Precipitation/PET, is the aridity index (AI), with an AI<0.2 indicating arid/hyperarid, and AI<0.5 indicating dry. [ 6 ] The coldest regions have not much evapotranspiration nor precipitation as there is not enough heat to evaporate much water, hence polar deserts .
Aridification is the process of a region becoming increasingly arid, or dry.It refers to long term change, [1] rather than seasonal variation. It is often measured as the reduction of average soil moisture content.