Changes

==Etymology==

==Etymology==

French or [[Latin]]; French aride, from Latin aridus, from arēre to be dry; akin to [[Sanskrit]] āsa ash, [https://nordan.daynal.org/wiki/index.php?title=English#ca._600-1100.09THE_OLD_ENGLISH.2C_OR_ANGLO-SAXON_PERIOD Old English] asce

French or [[Latin]]; French aride, from Latin aridus, from arēre to be dry; akin to [[Sanskrit]] āsa ash, [https://nordan.daynal.org/wiki/index.php?title=English#ca._600-1100.09THE_OLD_ENGLISH.2C_OR_ANGLO-SAXON_PERIOD Old English] asce

*Date: [http://www.wikpedia.org/wiki/17th_Century 1652]

*Date: [https://www.wikpedia.org/wiki/17th_Century 1652]

==Definitions==

==Definitions==

*1 : excessively dry; specifically : having insufficient rainfall to [[support]] [[agriculture]]

*1 : excessively dry; specifically : having insufficient rainfall to [[support]] [[agriculture]]

*2 : lacking in interest and life : jejune

*2 : lacking in interest and life : jejune

==Description==

==Description==

A region is said to be '''arid''' when it is characterized by a severe lack of available [[water]], to the extent of hindering or even preventing the [[growth]] and [[development]] of [[plant]] and [[animal]] life. As a result, [[environments]] subject to arid [[climates]] tend to lack [[vegetation]] and are called [http://en.wikipedia.org/wiki/Deserts_and_xeric_shrublands xeric] or [http://en.wikipedia.org/wiki/Desert desertic].

A region is said to be '''arid''' when it is characterized by a severe lack of available [[water]], to the extent of hindering or even preventing the [[growth]] and [[development]] of [[plant]] and [[animal]] life. As a result, [[environments]] subject to arid [[climates]] tend to lack [[vegetation]] and are called [https://en.wikipedia.org/wiki/Deserts_and_xeric_shrublands xeric] or [https://en.wikipedia.org/wiki/Desert desertic].

The [[expression]] 'available water' refers to [[water]] in the [[soil]] in excess to the wilting point. The [[air]] over a hot desert may actually contain substantial amounts of [[water]] [[vapor]] but that water may not be generally accessible to [[plants]], except for very specialized [[organisms]] (such as some species of [http://en.wikipedia.org/wiki/Lichen lichen]). 'Lack of water' refers to use by [[plants]]. The water that is actually present in the [[environment]] may be sufficient for some [[species]] or usages (such as climax vegetation), and grossly insufficient for others. Aridity, the characteristic [[nature]] of an arid [[climate]], may thus depend on the use of the [[land]]. Regards to the [[presence]] of life, what is more important than the [[degree]] of rainfall is the [[fraction]] of [[precipitation]] that is not quickly lost through [[evaporation]] or runoff. Attempts to [[quantitatively]] describe the [[degree]] of aridity of a place has often led to the development of [http://en.wikipedia.org/wiki/Aridity_index aridity indexes]. There is no [[universal]] [[agreement]] on the precise boundaries between [[classes]] such as 'hyper-arid', 'arid', 'semi-arid', etc.

The [[expression]] 'available water' refers to [[water]] in the [[soil]] in excess to the wilting point. The [[air]] over a hot desert may actually contain substantial amounts of [[water]] [[vapor]] but that water may not be generally accessible to [[plants]], except for very specialized [[organisms]] (such as some species of [https://en.wikipedia.org/wiki/Lichen lichen]). 'Lack of water' refers to use by [[plants]]. The water that is actually present in the [[environment]] may be sufficient for some [[species]] or usages (such as climax vegetation), and grossly insufficient for others. Aridity, the characteristic [[nature]] of an arid [[climate]], may thus depend on the use of the [[land]]. Regards to the [[presence]] of life, what is more important than the [[degree]] of rainfall is the [[fraction]] of [[precipitation]] that is not quickly lost through [[evaporation]] or runoff. Attempts to [[quantitatively]] describe the [[degree]] of aridity of a place has often led to the development of [https://en.wikipedia.org/wiki/Aridity_index aridity indexes]. There is no [[universal]] [[agreement]] on the precise boundaries between [[classes]] such as 'hyper-arid', 'arid', 'semi-arid', etc.

==Geographic Distribution==

==Geographic Distribution==

If [[different]] classification [[schemes]] and maps differ in their details, there is a general [[agreement]] about the [[fact]] that large areas of the [[Earth]] are considered arid. These include the hot [[desert]]s located broadly in sub-tropical regions, where the accumulation of water is largely prevented by either low [[precipitation]]s, or high [[evaporation]], or both, as well as cold deserts near the poles, where water may be permanently locked in solid forms (snow and ice). Other arid regions include areas located in the [http://en.wikipedia.org/wiki/Rain_shadow rain shadows] of major [[mountain]] ranges or along coastal regions affected by significant upwelling (such as the [http://en.wikipedia.org/wiki/Atacama_Desert Atacama Desert]).[http://en.wikipedia.org/wiki/Aridity]

If [[different]] classification [[schemes]] and maps differ in their details, there is a general [[agreement]] about the [[fact]] that large areas of the [[Earth]] are considered arid. These include the hot [[desert]]s located broadly in sub-tropical regions, where the accumulation of water is largely prevented by either low [[precipitation]]s, or high [[evaporation]], or both, as well as cold deserts near the poles, where water may be permanently locked in solid forms (snow and ice). Other arid regions include areas located in the [https://en.wikipedia.org/wiki/Rain_shadow rain shadows] of major [[mountain]] ranges or along coastal regions affected by significant upwelling (such as the [https://en.wikipedia.org/wiki/Atacama_Desert Atacama Desert]).[https://en.wikipedia.org/wiki/Aridity]

[[Category: Geography]]

[[Category: Geography]]