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 ?
According to the Assistant Secretary Alexander Pama of the National Disaster Risk Reduction and Management Council (NDRRMC) seven people were reported missing in three villages in the province of Bukidnon following several hours of heavy rains caused by the presence of an inter-tropical convergence zone and southwest monsoon.
Stormy weather spawned by the inter-tropical convergence zone (ITCZ) has hit the city since last week, prompting the mayor to immediately issue a weather alert, putting on standby the (CDRRMO)and other agencies responsible for emergency response.
These strong airflows from the south, pushed the so-called Inter-tropical Convergence Zone so far north that its southern extremity barely reaches northern Angola.
The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) is monitoring a new low pressure area (LPA) spotted 295 kilometers east of Mindanao and embedded along the inter-tropical convergence zone (ITCZ) across the Visayas.
The so-called Inter-Tropical Convergence Zone which is the most important conveyor and container of moisture for us, is also now far removed to the north, only showing up on synoptic maps some 1000 km away from the Namibia Angola border.
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.
He also said that inter-tropical convergence zone (ITCZ) is affecting Mindanao while the northeast monsoon has affected Northern Luzon, that brought rains yesterday.
The Inter-Tropical Convergence Zone has moved further north by some 800 km and is now situated over central Angola from west to east.
The potential cyclone, seen to trigger the start of rainy season if it intensifies, was last seen 580 kilometers east of Hinatuan, Surigao Del Sur and was embbeded along the inter-tropical convergence zone as of 8 a.
During the period, rain-causing weather systems, such as thunderstorms, tropical cyclones and inter-tropical convergence zone will dominate the season bringing heavy rainfall and strong winds, it added.
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, 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.

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