@prefix qx8: . @prefix skos: . @prefix chc: . qx8: a skos:ConceptScheme . qx8:-5BX5KB7N-9 skos:prefLabel "atmospherical phenomenon"@en, "phénomène atmosphérique"@fr ; a skos:Concept ; skos:narrower qx8:-9BWBXZ7C-Z . qx8:-9BWBXZ7C-Z skos:altLabel "ZCIT"@fr, "zone de convergence équatoriale"@fr, "ITCZ"@en, "zone intertropicale de convergence"@fr, "ZIC"@fr, "front intertropical"@fr ; skos:exactMatch , chc:-MNSP9X6V-L, ; skos:definition "La zone de convergence intertropicale (ZCIT), également connue sous le nom de zone intertropicale de convergence (ZIC), de front intertropical, de zone de convergence équatoriale ou plus familièrement pour les marins de « Pot au noir », est une ceinture de quelques centaines de kilomètres du nord au sud, de zones de basses pressions entourant la Terre près de l'équateur. Elle est formée par la convergence des masses d'air chaudes et humides anticycloniques provenant des tropiques portées par les alizés. Elle est caractérisée par des mouvements convectifs des cellules de Hadley et, en règle générale, par des formations importantes de cumulonimbus. La localisation de la zone de convergence intertropicale oscille autour de l'Équateur, passant de l'hémisphère nord à l'hémisphère sud et vice-versa selon un rythme annuel, suivant la déclinaison du Soleil. On observe aussi un cycle diurne, où les cumulus de l'avant-midi deviennent des orages à la fin de l'après-midi. En climatologie, la ZCIT correspond à l’équateur météorologique (EM). Ses variations ont un effet important sur les précipitations pour plusieurs nations équatoriales, produisant les saisons sèches et les saisons humides (moussons). Des anomalies prolongées de la ZCIT peuvent produire des épisodes météorologiques extrêmes dans les zones intertropicales. On retrouve des vents calmes ou faibles et de direction variable dans les basses couches de l'atmosphère au voisinage de la ZCIT. Ces calmes équatoriaux suivent, avec un léger retard, le déplacement méridien annuel. Le réchauffement climatique aura pour effet un déplacement vers le nord de la zone de convergence intertropicale. (Adapté de : https://fr.wikipedia.org/wiki/Zone_de_convergence_intertropicale)"@fr, "The Intertropical Convergence Zone (ITCZ /ɪtʃ/ ITCH, or ICZ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal equator though its specific position varies seasonally. When it lies near the geographic Equator, it is called the near-equatorial trough. Where the ITCZ is drawn into and merges with a monsoonal circulation, it is sometimes referred to as a monsoon trough (a usage that is more common in Australia and parts of Asia). The ITCZ appears as a band of clouds, usually thunderstorms, that encircle the globe near the Equator. In the Northern Hemisphere, the trade winds move in a southwestward direction from the northeast, while in the Southern Hemisphere, they move northwestward from the southeast. When the ITCZ is positioned north or south of the Equator, these directions change according to the Coriolis effect imparted by Earth's rotation. For instance, when the ITCZ is situated north of the Equator, the southeast trade wind changes to a southwest wind as it crosses the Equator. The ITCZ is formed by vertical motion largely appearing as convective activity of thunderstorms driven by solar heating, which effectively draw air in; these are the trade winds. The ITCZ is effectively a tracer of the ascending branch of the Hadley cell and is wet. The dry descending branch is the horse latitudes. The location of the ITCZ gradually varies with the seasons, roughly corresponding with the location of the thermal equator. As the heat capacity of the oceans is greater than air over land, migration is more prominent over land. Over the oceans, where the convergence zone is better defined, the seasonal cycle is more subtle, as the convection is constrained by the distribution of ocean temperatures. Sometimes, a double ITCZ forms, with one located north and another south of the Equator, one of which is usually stronger than the other. When this occurs, a narrow ridge of high pressure forms between the two convergence zones. Based on paleoclimate proxies, the position and intensity of the ITCZ varied in prehistoric times along with changes in global climate. During Heinrich events within the last 100 ka, a southward shift of the ITCZ coincided with the intensification of the Northern Hemisphere Hadley cell coincident with weakening of the Southern Hemisphere Hadley cell. The ITCZ shifted north during the mid-Holocene but migrated south following changes in insolation during the late-Holocene towards its current position. The ITCZ has also undergone periods of contraction and expansion within the last millennium. A southward shift of the ITCZ commencing after the 1950s and continuing into the 1980s may have been associated with cooling induced by aerosols in the Northern Hemisphere based on results from climate models; a northward rebound began subsequently following forced changes in the gradient in temperature between the Northern and Southern hemispheres. These fluctuations in ITCZ positioning had robust effects on climate; for instance, displacement of the ITCZ may have led to drought in the Sahel in the 1980s. Less certain are the regional and global shifts in ITCZ position as a result of climate change, with paleoclimate data and model simulations highlighting contrasts stemming from asymmetries in forcing from aerosols, voclanic activity, and orbital variations, as well as uncertainties associated with changes in monsoons and the Atlantic meridional overturning circulation. The climate simulations run as part of Coupled Model Intercomparison Project Phase 5 (CMIP5) did not show a consistent global displacement of the ITCZ under anthropogenic climate change. In contrast, most of the same simulations show narrowing and intensification under the same prescribed conditions. However, simulations in Coupled Model Intercomparison Project Phase 6 (CMIP6) have shown greater agreement over some regional shifts of the ITCZ in response to anthropogenic climate change, including a northward displacement over the Indian Ocean and eastern Africa and a southward displacement over the eastern Pacific and Atlantic oceans. (Adapted from: https://en.wikipedia.org/wiki/Intertropical_Convergence_Zone)"@en ; skos:prefLabel "zone de convergence intertropicale"@fr, "Intertropical Convergence Zone"@en ; skos:broader qx8:-5BX5KB7N-9 ; skos:inScheme qx8: ; a skos:Concept .