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 ?
14]C samples in Japanese dating laboratories, and Julian Sachs (University of Washington) for ITCZ precipitation variability.
But, the storm clouds in the ITCZ can merge to create towering thunderclouds whose upper reaches are higher than most commercial planes fly.
The presence of ITCZ will bring cloudy skies with light to moderate rains and isolated thunderstorms over Western Visayas, Davao region, Northern Mindanao and the provinces of Mindoro.
We designed a series of model experiments to examine how effective thermal forcing in different latitude bands is at shifting the ITCZ.
The potential of a flood-plume leading to inshore warm water presence (sea-surface temperatures in excess of 25[degrees]C) only bodes well where the arena for tropical low pressure cells, associated with the ITCZ, is concerned.
This equatorial low has an ITCZ footprint with this cross-continental inflow.
ITCZ is the thick clouds coming from the south of Asia and is considered a breeding ground for low-pressure areas or potential cyclones.
High Pressure cores (frequently stronger than 1030hPa) enable steady outflows of the Trades to maintain cooler air advection toward the ITCZ.
Meanwhile, due to the ITCZ, Mindanao, Western Visayas and Palawan would experience cloudy skies with scattered rains and thunderstorms.
The defined ITCZ trough line lay from Angola, across Zambia, across the ocean to Australia, thence past New Zealand, only fading to allow Trade Wind flows to be maintained across the broad Pacific, where the north-south lie of the anticyclonic core saw La Nina still in control.
Due to the ITCZ, Mindanao and the regions of Mimaropa and western Visayas are expected to experience scattered rains with thunderstorms.
Light to moderate rains are expected in the regions of Davao and SOCCSKSARGEN and the province of Surigao Del Sur because of the ITCZ, which is considered as breeding ground for low pressure areas.