aridity

meteorology

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June 18, 2026

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Aridity refers to a state of extreme dryness, characterized by a lack of moisture. In meteorology, this condition is primarily associated with desert climates, specifically tropical and subtropical desert climates (BWh and BWk). These climates are dominated by subtropical anticyclones, which cause descending air, elevated inversions, and clear skies, inhibiting precipitation.123

Key characteristics of arid environments include:
* Low Precipitation: Annual rainfall is typically very low, often below 250 mm (10 inches), and can be highly unreliable, with years of drought punctuated by rare, heavy downpours.34
* High Evaporation Rates: Potential evaporation rates are high, often exceeding precipitation significantly.4
* Temperature Extremes: Hot deserts experience very high daytime temperatures, with significant drops at night due to the lack of cloud cover.34

Aridity is a fundamental characteristic of deserts, defined by a moisture shortage that results from an imbalance between precipitation and evapotranspiration.4

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climate
Average relative humidity
…of the Northern Hemisphere when aridity is at a maximum. At other times the relative humidity generally will be higher. The humidities over the Southern Hemisphere in July indicate the humidities that comparable regions in the Northern Hemisphere will attain in January, just as July in the Northern Hemisphere suggests…
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…of the Northern Hemisphere when aridity is at a maximum. At other times the relative humidity generally will be higher. The humidities over the Southern Hemisphere in July indicate the humidities that comparable regions in the Northern Hemisphere will attain in January, just as July in the Northern Hemisphere suggests…
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river
Environments of deposition
…downstream into a progressively more arid environment, the probability of deposition is high. Thousands of metres of alluvial fan deposits flank the mountains of the western United States, the basin-and-range terrain of Iran and Pakistan, and similar desert regions (see below). In the arid climates of these areas the sediment…
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…downstream into a progressively more arid environment, the probability of deposition is high. Thousands of metres of alluvial fan deposits flank the mountains of the western United States, the basin-and-range terrain of Iran and Pakistan, and similar desert regions (see below). In the arid climates of these areas the sediment…
Read More