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Archive for Image of the day

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.

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.

Sediments Clouding Lake Erie, Canada and USA – November 28th, 2009

42.0N 81.3W

November 28th, 2009 Category: Image of the day, Lakes, Rivers

USA - November 8th, 2009

USA - November 8th, 2009

The waters of Lake Erie (below) are clouded by tan sediments, particularly along the upper shoreline to the left, while those of Lake Ontario (above) are much clearer with the exception of a small stretch along the southern shore.

Lake Erie is the fourth largest lake (by surface area) of the five Great Lakes in North America. It is the southernmost, shallowest, and smallest by volume of the Great Lakes, and therefore also has the shortest average water residence time. Lake Erie drains via the Niagara River and Niagara Falls into Lake Ontario.

It is bounded on the north by the Canadian province of Ontario, on the south by the U.S. states of Ohio, Pennsylvania, and New York, and on the west by the state of Michigan.

Green Fields of the Gezira Scheme in Sudan – November 27th, 2009

14.5N 33.1E

November 27th, 2009 Category: Image of the day, Rivers

Sudan - October 7th, 2009

Sudan - October 7th, 2009

The green irrigated fields of the Gezira Scheme in Sudan’s Al Jazirah state fill the land between the Blue (right) and White Nile (left) Rivers. The Gezira Scheme, begun by the British in 1925 to foster cotton farming, distributes water from the Blue Nile through canals and ditches to tenant farms lying between the two rivers.

Since the start of the scheme, Al Jazirah has become Sudan’s major agricultural region, with more than 2.5 million acres (10,000 km²) under cultivation. The initial development project was semi-private, but the government nationalized it in 1950. Cotton production increased in the 1970s but by the 1990s increased wheat production has supplanted a third of the land formerly seeded with cotton.

Volcanoes on Coastal Plain of El Salvador – November 26th, 2009

13.4N 88.1W

November 26th, 2009 Category: Image of the day, Volcanoes

El Salvador - November 14th, 2009

El Salvador - November 14th, 2009

Many volcanic peaks dot the landscape of central-eastern El Salvador, to the east of the Lempa River and north of Jiquilisco Bay, in this orthorectified image. To the east of these clusters of volcanoes is San Miguel, the fourth most populous city in El Salvador.

San Miguel is also the name of the stratovolcano located about 15km southwest of the city. The volcano, also known as Chaparrastique, is one of the most active volcanoes in the country.

North of the San Miguel volcano is Chinameca (also known as El Pacayal), a stratovolcano that rises over the town of Chinameca. The volcano is topped by a 2 km wide caldera known as Laguna Seca del Pacayal. A satellite cone on the west side, Cerro el Limbo, rises higher than the caldera rim. Fumaroles can be found on the north side, and it has been the site of a geothermal exploration program.

Continuing westward, the large stratovolcano Usulután can be identified as the peak on the coastal plain closest to the bay. The volcano is topped by a 1.3 km wide summit crater which is breached to the east.

West of Usulután is the Taburete stratovolcano. It is topped by a well-preserved, 150-300 m (500–1000 ft) deep summit crater, with the true summit on the south side of the crater rim.