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Archive for November 29th, 2009

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.

Photosynthetic Activity of Italy and Coastal Tunisia and Algeria

40.2N 13.3E

November 29th, 2009 Category: Snapshots

Italy - November 17th, 2009

Italy - November 17th, 2009

This FAPAR image shows the vegetation index of Italy, including the islands of Sardinia and Sicily, as well as Corsica and parts of coastal Tunisia and Algeria. The vegetation index corresponds to the Fraction of Absorbed Photosynthetically Active Radiation, which provides data on the planet’s climate system.

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 appear blue. Dark red regions correspond to agricultural zones for which there is high photosynthetic activity and therefore vegetation productivity, while yellow to white areas, with the exception of white patches of clouds,  indicate a low degree of photosynthetic activity.

Here, some red areas can be seen on the islands of Sardinia and Sicily, while most of Italy and Corsica appears green with some yellow zones. Algeria and Tunisia show photosynthetic activity near the coast, while the area further south is yellow and white, reflecting the low photosynthetic activity of more arid regions.

Nida (26W) Becomes Category 5 Super Typhoon – November 29th, 2009

20.4N 137.8E

November 29th, 2009 Category: Image of the day, Tropical Cyclones

Typhoon Nida (26W) - November 28th, 2009

Typhoon Nida (26W) - November 28th, 2009

Track of STY 26W - November 28th, 2009 © Univ. of Wisconsin

Track of STY 26W

Enhanced image

Enhanced image

Super Typhoon Nida (STY 26w), located approximately 350 nautical miles south-southwest of Iwo To, has tracked north-northeastward at 2 knots over the past six hours. Maximum significant wave height is 34 feet.

Maximum sustained winds are at 140 knots, with stronger gusts of up to 170 knots. Winds of 64 knots extend outward for a radius of 50 to 55 nautical miles from the eye of the storm, while the radius of winds of up to 50 knots is 75 to 80 nautical miles.