intertropical convergence zone

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intertropical convergence zone

[¦in·tər′träp·ə·kəl kən′vər·jəns ‚zōn]
(meteorology)
The axis, or a portion thereof, of the broad trade-wind current of the tropics; this axis is the dividing line between the southeast trades and the northeast trades (of the Southern and Northern hemispheres, respectively). Also known as equatorial convergence zone; meteorological equator.

Intertropical Convergence Zone

 

an intermediate zone, several hundred kilometers wide, between the trade winds of the northern and southern hemispheres. For most of the year, the intertropical convergence zone is located north of the equator; during the northern hemisphere’s winter it nears the equator (and can sometimes penetrate into the southern hemisphere), and during the summer it recedes from it. Over the Atlantic and Pacific oceans, seasonal displacements of the intertropical convergence zone are not great; they are greater over Africa and South America, but they are particularly significant in the basin of the Indian Ocean, where trade-wind circulation over extensive areas is replaced by monsoon circulation. Considerable shifts in the intertropical convergence zone are frequently observed even from one day to the next.

In general, the intertropical convergence zone coincides with the equatorial depression—that is, with a low-pressure belt situated between the subtropical high-pressure zones of the northern and southern hemispheres. In this zone, in addition to light, variable winds, squalls and winds with a pronounced general easterly or westerly direction are observed. The nature of the weather in the intertropical convergence zone differs sharply from the weather in the trade-wind zones. Convection here is accelerated by the confluence of lines of flow; there is increased cloudiness, the clouds reach great heights, and abundant precipitation falls from them.

The intertropical convergence zone, as a rule, is not uniform in its breadth and properties; wave and vortex perturbations arise in it, leading to the formation of separate cloud clusters. The overwhelming majority of tropical cyclones with storm winds and catastrophic consequences form in this zone.

REFERENCE

Riehl, H. Tropicheskaia meteorologiia. Moscow, 1963. (Translated from English.)

S. P. KHROMOV

intertropical convergence zone (ITCZ)

The boundary zone between the tradewinds of the Northern and the Southern Hemispheres. It is characterized in maritime climates by overcast skies, showers, and precipitation, with cumulus clouds sometimes extending to great heights.
References in periodicals archive ?
The eastern parts of the sub-continent show a recurrent style representative of the Inter-Tropical Convergence Zone of summer.
The position of the Inter-Tropical Convergence Zone is unclear on our northern border, but the outlooks offer an improving chance for advancing both moist lower level air and some weakening of the upper air grip.
The Inter-Tropical Convergence Zone, the ITCZ, sits prominently across southern Africa at an east west line more or less on the border between Owambo and Angola, stretching all the way to the east as far as the Mozambican Channel where another dominant low pressure system is developing.
The Inter-tropical Convergence Zone, having shifted east for about two weeks, is migrating back west and sits over southern Angola.
The Inter-Tropical Convergence Zone has moved further north by some 800 km and is now situated over central Angola from west to east.
According to a report by the National Disaster Risk Reduction and Management Council (NDRRMC), an Inter-Tropical convergence zone (ITCZ) had affected the islands of Mindanao, Visayas and Southern Luzon's Bicol Region from last week causing flash floods and landslides.
For seven of the past nine summers, this has created space for the Inter-Tropical Convergence Zone, where moist air rules, to wander further south, bringing above normal precipitation to Namibia.
Inter-Tropical Convergence Zone causing widespread rains across several hundred kilometres in the belt south of the Angola border.
Wind flow will remain north easterly, gradually setting the stage for the Inter-Tropical Convergence Zone to wander southward and herald the new rain season.
The Inter-Tropical Convergence Zone remained fairly well marked across the continent from Angola to Tanzania, extending around the globe to the Pacific on the opposite side.
Equatorial activity with the Inter-Tropical Convergence Zone (ITCZ) as the mainspring, has ensured the presence of moist Congo air across our northern borders.
Still the Inter-Tropical Convergence Zone maintained its position just north of the Owambo Angola border with some influx into our territory.

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