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Archive for November, 2009

The Kyzylsu River and Mountains of Southern Tajikistan

37.9N 69.7E

November 30th, 2009 Category: Rivers

Tajikistan - October 5th, 2009

Tajikistan - October 5th, 2009

Landlocked Tajikistan is the smallest nation in Central Asia by area. It is covered by mountains of the Pamir range, and more than fifty percent of the country is over 3,000 meters (approx. 10,000 ft) above sea level. This orthorectified image focuses on the mountains in the south near the city of Tulob (or Tulyab) and the border with Afghanistan.

Visible in the Kyzylsu Valley (left) is the Kyzylsu River, which rises on the southern slopes of the Vakhsh Range in the north-east of Tajikistan’s Khatlon Province and runs south-west for a length of 230 km until joining Panj River on the border with Afghanistan. Near Kulob it merges with the Yakhsu River as a major left tributary. The river irrigates the cotton-growing Kyzylsu Valley between Kulob and Panj in the south-east of Khatlon Province.

Pinacate Peaks Amidst Sand Dunes of the Gran Desierto de Altar, Mexico

31.7N 114.7W

November 30th, 2009 Category: Rivers, Volcanoes

Mexico - November 17th, 2009

Mexico - November 17th, 2009

The Colorado River pours thick tan sediments around Montague Island and into the Sea of Cortes. The sediments gradually take on a greenish appearance as they diffuse southward.

North of the rivermouth is the Gran Desierto de Altar, part of the Sonoran Desert. The desert’s vast sand dune field appears mostly tan here, with the exception of a dark brown circular area in the upper right quadrant.

This part of the desert is the location of the Pinacate Peaks, a group of volcanic peaks and cinder cones. The tallest of the peaks is Cerro del Pinacate (also called Volcan Santa Clara), elevation 3,904 feet (1,190 m).

Vegetation Index of Ghana, Togo, Benin and Nigeria

10.3N 4.6E

November 30th, 2009 Category: Climate Change, Lakes

Nigeria, Benin, Togo & Ghana - November 17th, 2009

Nigeria, Benin, Togo & Ghana - November 17th, 2009

This FAPAR image stretches along the coast of Africa, from Ghana (left), across Togo and Benin, to Nigeria (right). FAPAR stands for Fraction of Absorbed Photosynthetically Active Radiation, which corresponds to the  area’s vegetation index.

In FAPAR images, the color spectrum over land runs from red (1.0), to green, to yellow and white (0.0), while bodies of water, such as Lake Volta in Ghana  (lower left) and Lake Kainji in Nigeria (center), generally appear blue.

High photosynthetic activity is present in dark red regions, such as those along the coast here. Green areas are also productive. Yellow to white areas, on the other hand, indicate a low degree of photosynthetic activity. Here, the more photosynthetically active green areas gradually give way to less activa yellow and white zones as one approaches the drier Sahel, south of the Sahara desert.

Mount Nemrut and Arms of Lake Van, Turkey – November 30th, 2009

38.6N 42.9E

November 30th, 2009 Category: Image of the day, Lakes, Volcanoes

Turkey - November 24th, 2009

Turkey - November 24th, 2009

Lake Van is one of the largest endorheic lakes in the world and the largest lake in Turkey, located in the far east of the country in the Van district. It is a saline and soda lake, receiving water from numerous small streams that descend from the surrounding mountains. Here, the Nemrut Volcano can also be seen west of the lake, partially covered with snow.

The lake’s average depth is 171 metres (560 ft) with a maximum recorded depth of 451 metres (1,480 ft). The western portion of the lake is deepest, with a large basin deeper than 400 m (1,300 ft) lying northeast of Tatvan and south of Ahlat. This deeper section of the lake appears navy blue here.

The eastern arms of the lake, on the other hand, are shallower and appear greenish from sediments and algae. The Van-Ahtamar portion, southeast, shelves gradually, with a maximum depth of about 250 m (820 ft) on its northwest side where it joins the rest of the lake. The Erciş arm, northeast, is much shallower, mostly less than 50 m (160 ft), with a maximum depth of about 150 m (490 ft).

Over 100 species of phytoplankton have been recorded in the lake including flagellates, diatoms, bacteria, cyanobacteria, green algae and brown algae. Thirty-six species of zooplankton have also been recorded including Rotatoria, Cladocera and Copepoda in the lake.

Sobradinho Reservoir on the São Francisco River, Brazil

9.6S 41.5W

November 29th, 2009 Category: Lakes, Rivers

Brazil - November 15th, 2009

Brazil - November 15th, 2009

Sobradinho Lake is one of the largest artificial reservoirs in the world, with an area of 4,214 square kilometres (1,627 sq mi). It lies along the São Francisco River, in the Brazilian state of Bahia.

The Sobradinho Dam, built in 1977 and one of four hydroelectric plants along the course of the river, has storage capacity of 34.1 billion m3 of water.

The lower end of the reservoir appears tan in color, as it is filled with sediments where the São Francisco River spills into it. The color appears more greenish where the river exits after flowing through the dam.