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Sun Glint on Rivers Crossing Amazon Rainforest, Brazil

2.4S 66.5W

March 26th, 2013 Category: Rivers

Brazil – March 26th, 2013

The Amazon River and several of its tributaries can be seen flowing across this image, amidst the green vegetation of the Amazon Rainforest in the Brazilian state of Amazonas. The rivers appear silver in color due to sun glint. Despite the lush green of the vegetation visible here, the Amazon Biome is threatened by climate change and deforestation, resulting in the substitution of forests with savanna-like and semiarid vegetation in many areas.

Fields of Sand Dunes Along Coast of Northeast Brazil

2.8S 40.5W

February 18th, 2013 Category: Deserts

Brazil – January 19th, 2013

The northeast of Brazil (known locally as the Nordeste region) is characterized by semi dessertic weather and characteristics such as hot and dry temperatures, drought, lack of or scant rainfall, eroded soil and high evapotranspiration. Many coastal areas in region are covered by vast fields of active and stabilized coastal sand dunes.

Scientific studies show the vast prevalence of active sand dunes along the coast of NE Brazil in a tropical climate (average yearly rainfall above 1000 mm) results from the high powered trade winds, mostly during the dry season. Many stabilized dunes are found along this coast, side by side with the active dunes. A hysteresis model based on changes in wind power can explain the co-existence of stabilized and active dunes in the same area.

Vegetation on sand dunes in NE Brazil thrives when the rainfall is above 400 mm and the wind power is low. The dunes during the wetter periods were stabilized by vegetation due to low wind power and not because of the increased precipitation (click here for more information).

Convergence of Branco and Negro Rivers, Brazil – February 9th, 2013

1.4S 61.6W

February 9th, 2013 Category: Image of the day, Rivers

Brazil – January 23rd, 2013

This image of the Amazon Rainforest, in Brazil, also shows the confluence of the Branco River (right) and Negro River (left), near the border of the states of Amazonas and Roraima. The Rio Branco (meaning White River) is the principal affluent of the Rio Negro (meaning Black River) from the north.The Branco flows nearly south, and finds its way into the Negro through several channels and a chain of lagoons similar to those of the latter river. It is 350 miles (560 km) long.

The Rio Negro, in turn, is the largest left tributary of the Amazon and the largest blackwater river in the world. It flows into the Rio Solimões to form the Amazon River South of Manaus, Brazil. Rio Negro is navigable for 700 kilometres (430 mi) from its mouth in 1 metre of water in the dry season, but it has many sandbanks and minor difficulties. In the wet season, it floods the country far and wide, sometimes to a width of 30 kilometres (19 mi), for long distances, and for 650 kilometres (400 mi) upstream. During this time, from April until October, it is a succession of lagoons, full of long islands and intricate channels.

Sunglint on Reservoir of Engineer Sérgio Motta Dam, Brazil

22.5S 53W

February 8th, 2013 Category: Lakes

Brazil – January 22nd, 2013

Sunlight reflecting off the surface off the reservoir created by the Engineer Sérgio Motta Dam gives the lake a bright whitish-silver color. The sun glint also highlights the contours and irregular shoreline of parts of the reservoir. The dam, formerly known as the Porto Primavera Dam, is an embankment dam on the Paraná River near Rosana in São Paulo, Brazil. It was constructed between 1980 and 1999 for hydroelectric power production, flood control and navigation. At 11.380 km (7.071 mi) in length, it is the longest dam in Brazil. The 22 m (72 ft) tall dam creates a reservoir with a 19.9 km3 (4.8 cu mi) capacity and surface area of 2,250 km2 (870 sq mi).

Sediments in Lagoa Mirim and Lagoa dos Patos, Brazil and Uruguay

32.7S 52.7W

December 3rd, 2012 Category: Lakes, Sediments

Uruguay and Brazil – December 2nd, 2012

Lagoa Mirim, as it is known in Brazil, or Laguna Merín in Uruguay, is a large estuarine lagoon which extends from the southern Rio Grande do Sul state in Brazil into eastern Uruguay. Lagoa Mirim is about 108 miles (174 km) long by 6 to 22 miles (35 km) wide.

Lagoa Mirim is separated from the Atlantic Ocean by a sandy, partially barren isthmus. It is more irregular in outline than its larger neighbor to the north, Lagoa dos Patos, and discharges into the latter through São Gonçalo Channel, which is navigable by small boats. Here, Lagoa Mirim appears greyish brown, while its neighbor to the north shows a mix of dark brown, reddish tan and green.

Both lagoons are the remains of an ancient depression in the coastline shut in by sand beaches built up by the combined action of wind and oceanic currents. They are at the same level as the ocean, but their waters are affected by the tides and are brackish only a short distance above the Rio Grande outlet.