Chapada Diamantina is located within the Brazilian state of
Bahia and just 283 kilometers from the coast in Salvador.
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| Chapada Diamantina located in the Eastern Brazilian state of Bahia |
This region is
particularly known for experiencing the effects of surface winds during the summer
(austral) months in the southern hemisphere. These equatorial surface winds
occur within the Intertropical Convergence Zone or ITCZ. The ITCZ is a band of
low pressure circling the equator and is associated with strong rainfall.
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| Seasons in Southern vs. Northern Hemispheres |
The Third Law of Geography states that air always flows from
high pressure to low pressure. In the southern hemisphere during December,
January, and February the low pressurized Intertropical Convergence Zone is
pulled south and brings intense rainfall to Chapada Diamantina. The northern
hemisphere’s summer (boreal) months of June, July, and August causes the ITCZ
to travel north depriving Chapada Diamantina of rainfall.
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| ITCZ effects during Northern Hemisphere Boreal months vs. Southern Hemisphere Austral months |
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| Rainfall changes drastically based on which direction the ITCZ is being pulled |
The warm air in the Trade Winds flow towards the low
pressure in the Intertropical Convergence Zone and are responsible for many of
the weather patterns linked to this region. Trade Winds blow westward above and
below the equator. This combination causes upward winds as they are heated
resulting in a calm area known as doldrums.
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| Trade Winds converging above and below the equator as warm air rises producing clouds and rain |
Trade Winds are viable assets to ocean circulation near
Chapada Diamantina in Brazil. They drive the South Equatorial Current (SEC) and once
the current approaches Brazil it splits into both the Brazil and North Brazil
currents. This mix of major warm currents derives and produces giant
subtropical Gyres. Gyres are large circular ocean currents driven by
subtropical high pressure.
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| Major warm currents forming giant subtropical gyres |
Finally, every seven years or so pressure flip-flops and the result
is severe drought in Chapada Diamantina as well as other regions in Brazil. This
is due to El Niño Southern Oscillation (ENSO). El Niño effects are felt globally.
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| El Nino effects across the globe |
http://www.skepticalscience.com/print.php?n=740
http://www.pura-aventura.com/blog/chapada-diamantina-climate/
http://gosouthamerica.about.com/od/braregnortheast/p/ChapadaDiamant.htm
http://kids.earth.nasa.gov/archive/nino/global.html
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