Interropic convergence zone – Wikipedia

The thunderstorms of the intertropical convergence zone form a line across the east of the Pacific Ocean.

The Interropical convergence area ( Zcit ), also known as Convergence intertropical zone (I say), of front intertropical , of Equatorial convergence area Or more familiarly for sailors of ” Black pot “Is a belt of a few hundred kilometers from north to south, of low pressure zones surrounding the earth near the equator ^{[ first ]} .

It is formed by the convergence of the mass of hot and humid high -techlonic air from the tropics worn by the trade winds ^{[ first ]} . It is characterized by convective movements of Hadley cells and, as a rule, by important formations of cumulonimbus ^{[ 2 ]} .

Position of the ZCIT in January (in blue) and in July (in red).

The location of the intertropical convergence zone oscillates around the equator, passing from the northern hemisphere to the southern hemisphere and vice versa according to an annual rhythm, according to the declination of the sun ^{[ 2 ]} . We also observe a diurnal cycle, where the cumulus of the beforenoon become thunderstorms at the end of the afternoon.

In climatology, the ZCIT corresponds to the meteorological equator (EM). Its variations have an important effect on precipitation for several equatorial nations, producing dry seasons and humid seasons (monsoons) ^{[ 2 ]} . Prolonged ZCIT abnormalities can produce serious floods or droughts in intertropical zones.

There are calm or weak winds and variable steering in the low layers of the atmosphere in the vicinity of the ZCIT. These equatorial calm follow, with a slight delay, the annual meridian displacement ^{[ 3 ]} .

Marine [ modifier | Modifier and code ]

The intertropical zone was a serious concern for sailors until the end of the XIX ^{It is} century. Under these latitudes, sailing ships (especially the slowest of them) could remain encalminated for several days, even several weeks, in an unhealthy climate, with alternations of torrential rains, storm grains, crazy laughs and flat calm.
To the physical torments was added a demoralizing effect of helplessness in the face of the elements.

Nowadays, despite the progress of weather aid, the ZCIT remains a major or even decisive element, during ocean regattas, for the crossing of the meteorological equator ^{[ 4 ]} .

Different nicknames were given to this geographical area:

• the Pot-au-noir (France), evoking the black appearance of storm grains and the fact of being stuck there as in a trap (the expression pot-au-black was synonymous with trap XVIII ^{It is} century).

Another origin of this appellation is often mentioned although questioned by number of historians: slave ships are often blocked in this area, mortality among the cargo of slaves was important, and the crew threw corpses there . Hence the expression “black pot” or “black pot” ^{[ 5 ]} .

Finally, it should be noted that the Pot-au-Noir is approximately a little further north only of the Congolese coastal city of Pointe-Noire, for its African Atlantic part around January (map above).

• THE Doldrums (Old English word meaning wave to the soul, depressed, derived from the archaic word with meaning alienated, fool) which correspond to the central part of the ZCIT, around the equator. In the English language, imprint of nautical metaphors, the term DOLDRUMS is often used for economic slump, frozen political situations, etc.

Aviation [ modifier | Modifier and code ]

During the time of the Aéropostale and the first transatlantic flights of Jean Mermoz, on the Saint-Louis-du-Sénégal-Natal axis, therefore in full zcit, the violent storm grains were feared by flying aviators at low altitude and low speed with Magnetic instruments and inexperienced and not pressurized devices.

Radio noise [ modifier | Modifier and code ]

In the intertropical convergence zone, electric discharges and vigorous thunderstorms at every moment generate radio noises in the radios frequencies less than 2 MHz , making low frequency and medium frequency bands unusable.

Related article [ modifier | Modifier and code ]

• Bermuda triangle, which may make impacts and consequences of the ZCIT think, although the famous triangle is located outside the area around July (map), A stronger Around January.

external links [ modifier | Modifier and code ]