intertropical convergence zone


Also found in: Dictionary, Thesaurus, Acronyms, Wikipedia.

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 Philippine Atmospheric Geophysical and Astronomical Services Administration (Pagasa) said an Intertropical Convergence Zone (ITCZ) continues to affect Palawan, Visayas, and Mindanao on Friday.
The intertropical convergence zone is affecting Mindanao and Palawan, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said.
Cloudy skies with light to moderate rains and isolated thunderstorms will be experienced in most part of Philippines due to the Intertropical Convergence Zone (ITCZ) affecting Mindanao, the state weather bureau PAGASA said.
The Intertropical Convergence Zone (ITCZ) will affect parts of Mindanao while the northeasterly surface wind flow will affect the Northern Luzon, the state weather bureau said on Saturday.
The Intertropical Convergence Zone (ITCZ) will bring light to moderate rains to Visayas and Mindanao, the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) said, September 19, 2015.
Meanwhile, the intertropical convergence zone (ITCZ) will continue to affect the Davao region, Autonomous Region in Muslim Mindanao, Soccsksargen, Zamboanga Peninsula and Palawan, the Philippine Atmospheric Geophysical and Astronomical Service Administration (Pagasa) said.
The two LPAs are inside the intertropical convergence zone , the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) said.
The Visayas and Mindanao, along with Palawan and the Bicol Region, will experience scattered rain and thunderstorms on Tuesday due to the Intertropical Convergence Zone (ITCZ), the weather bureau said.