Thursday, November 13, 2014

Weather & Climate

Chapada Diamantina is located within the Brazilian state of Bahia and just 283 kilometers from the coast in Salvador. 
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.


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.
ITCZ effects during Northern Hemisphere Boreal months vs. Southern Hemisphere Austral months
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.
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.
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.
El Nino effects across the globe
References:
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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