The South Atlantic convergence zone, or SACZ, is an elongated axis of clouds,

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...

, and convergent winds oriented in a northwest–southeast manner across southeast Brazil into the southwest Atlantic Ocean. By definition, the feature is a

monsoon trough The monsoon trough is a portion of the Intertropical Convergence Zone in the Western Pacific,Bin WangThe Asian Monsoon.Retrieved 2008-05-03. as depicted by a line on a weather map showing the locations of minimum sea level pressure, and as such, ...

. It is strongest in the warm season.

Thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are someti ...

activity along the feature magnifies over three or more days when the

Madden–Julian oscillation The Madden–Julian oscillation (MJO) is the largest element of the intraseasonal (30- to 90-day) variability in the tropical atmosphere. It was discovered in 1971 by Roland Madden and Paul Julian of the American National Center for Atmospheric R ...

passes into the region, due to the enhanced upper divergence. Low level winds over

Rondônia Rondônia () is one of the 26 states of Brazil, located in the northern subdivision of the country (central-western part). To the west is a short border with the state of Acre, to the north is the state of Amazonas, in the east is Mato Grosso, ...

are tied to the strength of this zone, where westerly wind anomalies correlate to active phases of the South American

monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscil ...

, while easterly wind anomalies indicate breaks of activity along the SACZ. The feature is also strongest with negative anomalies in the

sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air mass ...

pattern lie over the southern Atlantic Ocean, while opposite conditions prevail across the northern Atlantic Ocean.

References

Tropical meteorology Atmospheric dynamics Regional climate effects {{climatology-stub