<Li> The Gran Chaco thermal low: A semi-permanent thermal - orographic depression located over the slope extending from Chaco to the Los Andes mountain range in the Argentine Northwest . It can be considered, together with the Bolivian High, as the regional response of the tropospheric circulation to the strong convective heating over the Amazon--central Brazil . The Andes effect reinforces the strength of the Chaco Low as an orographic barrier . It is present throughout the year, but is more intense during the summer, with a strong thermal component caused by the combination of high insolation and dry surface conditions . The resulting pressure gradient between the south Atlantic subtropical high and the Chaco low forces the easterly winds over the Amazon basin to turn southward, being channelled between the eastern slope of the Andes and the Brazilian Plateau . </Li> <Li> The South Atlantic Convergence Zone (SACZ): The SACZ controls rainfall in the southern subtropics and extends southeastward from the large continental convective zone of tropical South America . It is generated by moisture convergence between the South Atlantic high pressure zone and the continental thermal low pressure zone . The location of the SACZ is influenced by the topography in central - east Brazil Vera et al. (2006). The intensity of the SACZ is highest in austral summer, in phase with intensifying continental heating and convection . Weak SACZ is accompanied by enhanced rainfall over northern Argentina and southern Brazil . These positive rainfall anomalies are supported by a strong southward moisture flux at about 35 ° S--60 ° W that shifts eastward to about 40 ° W for the opposite phase of the seesaw, in accordance with an eastward displacement of the Atlantic high . An intensified SACZ is associated with enhanced streamflows to the north and diminished flows to the south . This north--south separation is probably related to the anomalously warm sea surface temperatures (SSTs) over the tropical and subtropical South Atlantic that strengthens the low - level meridional temperature gradient, intensifying the South Atlantic High and consequently the trade - winds . </Li> <Li> Polar outbreaks: Polar outbreaks occur when cold dense polar air masses pass beneath warmer tropical air masses, significantly cooling subtropical South America . They occur as a result of anticyclogenesis in the Pacific subtropical high, which is constrained at a low level by the southern extent of the Andes mountain range . This leads to the formation of a slow - moving long wave that creates mountain - parallel, ageostrophic flow, causing incursions of high - latitude cold air . They generate an important drop in temperature and increase in pressure, resulting in regional precipitation for southern South America . These surges occur mainly during the winter but their impact on the precipitation is even greater during summer . </Li> <Li> Low Level Jet (LLJ): LLJs originate in a low pressure area over the northern Andes and provide moisture for subtropical latitudes . During summer, they operate as localised wind maximum within the lower 1--2 km of the atmosphere, channelled by the Andes, terminating in southeastern South America . They are controlled by Amazonian wind patterns, which are influenced and controlled by patterns of insolation . They transport large amounts of moisture from the Amazon basin to the monsoonal anitcyclone over Bolivia . A suppressed SACZ and increased convection in the sub-tropical plains is associated with a strengthening of the LLJ . These phases are linked to short - term extreme precipitation events in the plains of central Argentina . When the LLJ is weak, there is enhanced SACZ and suppressed convection to the south and extreme heat waves over the sub-tropical regions . It also generates turbulence through shear and participates actively as trigging mechanism for the formation of severe storm and Mesoscale Convective Systems over Paraguay, Northern Argentina and South of Brazil . </Li>

How does physical geography affect the distribution of climate regions in latin america