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The airport lies 31 kilometers to the northeast of Munich. Rather than being an extension of the metropolis, the airport is surrounded by agricultural fields and small towns. The agricultural fields in active use appear in various shades of green, while the exposed soils of fallow fields appear brown to tan. Roadways around the airport appear as thin, intersecting lines. The white concrete airport runways are 4 kilometers in length. At bottom center, the magnified shadows of clouds hang over the scene.
The airport grew in 2003 with the addition of Terminal 2, designed specifically to accommodate the needs of Lufthansa and its partner airlines. This astronaut photograph, taken from the International Space Station, shows enough detail to distinguish individual airplanes on the terminal apron (inset; white rectangle marks location on main image), and the dark gray-blue rooftop of Terminal 2. Astronauts achieve this level of photographic detail—the image resolution approaches 4 meters/pixel—by manually tracking the motion of the ground as the spacecraft orbits the earth at more than 7 kilometers per second. This photo was taken at a relatively slow shutter speed (1/60 second), which equates to more than 100 meters of ground motion. Precise astronaut tracking is required to improve the resolution in detailed images taken with long lenses.
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This oblique (looking at an angle) astronaut photograph captures the dynamic nature of the landscape of Har Nuur. The lake is encircled by sand dune fields that encroach on the lower slopes of the Tobhata Mountains to the west and south. Gaps in the mountains have been exploited by sand dunes moving eastward, indicating westerly winds. The most striking example is a series of dunes entering Har Nuur along its southwestern shoreline. Here, the dune forms reflect the channeling of winds through the break in the mountain ridgeline, leading to dune crests lying perpendicular to northwesterly winds. Another well-developed line of dunes appears between Har and Baga Lakes; while these dunes appear to cut across a lake surface, the dunes have in fact moved across a narrow stream channel.
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This detailed astronaut photograph zooms in on a shipping channel in the western part of the delta. The straight channel is periodically dredged, and the dredged material is piled along the edge of the channel in mounds. Surrounding wetlands are partially inundated. Flood waters with muddy sediment stream from the distributaries along the channel, producing long streamers. This image was taken a few days after heavy rains in early September 2006 flooded parts of Russia to the north, and it captures the flood waters emptying into the Caspian Sea. Since 1978, the Caspian Sea level has risen over 2 meters (a little over 6 feet), submerging valuable wetland habitats, flooding coastlines, agricultural land, and industrial infrastructure. It has become a struggle for the nations surrounding the Caspian to maintain channels and coastal developments and to preserve natural marine and land habitats. Shallow coastlines like the Volga delta are particularly vulnerable to rising sea levels.
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Dark, curved lines on the inland (western) side of the spit show old positions of the spit. Most of Musallas Lagoon occupies the lower half of the image. By contrast with the spit, the shores of the lagoon are occupied almost entirely by a network of artificial structures—mainly short dikes enclosing hundreds of aquaculture ponds. The total area devoted to fish production in the lagoon is estimated to be 8,000 hectares (19,768 acres), which constitutes more than half of Egypt’s aquaculture production. An outlet to the Mediterranean Sea (top right) allows seawater recharge to the lagoon. Wind helps to circulate the water in this shallow lagoon; bright streaks on the lagoon (lower left) show the north-northwest direction of the wind on this day.
The intense aquaculture in the Nile Delta was born out of the impacts of the Aswan High Dam. The construction of the Aswan High Dam nearly a thousand kilometers upstream stopped the dramatic, and often catastrophic, seasonal floods that previously delivered nutrient-rich sediment from the Nile to the Mediterranean Sea. Nutrient concentration dropped to such a degree that the sea fishery around the delta collapsed in the mid-1960s to about 3 percent of the catch in preceding years. Aquaculture in various parts of Egypt during the last 30 years has partly made up for this loss, and consumption of fish has doubled in Egypt, although exports have not recovered.
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The Po River, Italy’s longest river, runs approximately 650 kilometers (400 miles) from the southwestern Alps to the Adriatic Sea, passing indirectly through Milan, and through Turin. As Turin is an industrial center of a heavily urbanized region, pollutants often cloud the skies overhead. In fact, northern Italy is one of Europe’s pollution hotspots, and the smog often grows thick enough to be seen from space. Smog in this area is so persistent that astronauts on the International Space Station have photographed other images of it, in October 1997 and February 2003. Recurring accumulations of smog in the Po River Valley, however, result from more than just the industrial emissions from the area around Turin. In this area, smog is often trapped at the base of the Alps by high atmospheric pressure.
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This image shows many features of the mine workings, such as the terraced levels and access roadways of the open mine pits (gray and tan sculptured surfaces). A large gray tailings pile of waste rock and an adjacent tailings pond appear to the north of the Berkeley Pit. Color changes in the tailings pond result primarily from changing water depth. Because its water contains high concentrations of metals such as copper and zinc, the Berkeley Pit is listed as a federal Superfund site. The Berkeley Pit receives groundwater flowing through the surrounding bedrock and acts as a “terminal pit” or sink for these heavy-metal-laden waters, which can be as strong as battery acid. Ongoing clean-up efforts include treating and diverting water at locations upstream of the pit to reduce inflow and decrease the risk of accidental release of contaminated water from the pit into local aquifers or surface streams.
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Two different types of river appear in this image: black-water rivers and white-water rivers. In addition to the Rio Negro, two other “black” rivers—Rio Caures and Rio Jufari—join the Rio Negro in the scene. At the right of the image is the Rio Branco (White River), which is the largest tributary of the Rio Negro. The difference in water color is controlled by the source regions. Black-water rivers derive entirely from soils of lowland forests, rich in leaves and other decaying organic matter. Water in these rivers has the color of weak tea, which appears black in images from space. By contrast, white-water rivers like the Branco arise in mountainous country where headwater streams erode exposed rock. White-water rivers carry a load of sand and mud particles, which lighten the waters. The Amazon itself rises in the Andes Mountains, where very high rates of erosion occur, and it is thus the most famous white river in Amazonia.
This astronaut photograph was taken in September, when the rivers are near their seasonal low-water stage. Pictures taken at other times show the channels to be much wider during high-water season (May–July), when water levels rise several meters. High-resolution GPS (Global Positioning System) measurements at Manaus recently documented that the land surface actually rises vertically a small amount when the vast mass of water drains away each season. Although the rebound amount seems small, the vertical displacement—50-70 millimeters—was unexpectedly large according to the scientists who performed the study.
- References
- Bevis, M., Alsdorf, D., Kendrick, E., Fortes, L.P., Forsberg, B., Smalley, R., Jr., and Becker, J. (2005). Seasonal fluctuations in the mass of the Amazon River system and Earth’s elastic response. Geophysical Research Letters,32, L16308, doi:10.1029/2005GL023491.
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Interestingly, the alluvial fan also acts as the only outlet of the lake, although no obvious outlet channel can be seen in this detailed astronaut photograph captured on September 4, 2006. South of the fan, an outlet river appears as a green surface, possibly due to aquatic vegetation or algae. Altitude measurements show that the outlet river lies many meters below the lake surface. This means that lake water drains slowly through the permeable sediments of the alluvial fan by subsurface flow, roughly following the line of the arrow. Another, smaller alluvial fan in the south constricts this outlet river.
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Linear dune chains are usually generated roughly parallel to the dominant winds. It also seems to be true that linear dunes are built by stronger winds. This detailed astronaut photograph shows that smaller dunes, known as star dunes, are built on top of the linear dunes. Star dunes seem to form in weak wind regimes, in which winds blow from different directions in each season, resulting in characteristic “arms” snaking away from a central point. Some scientists therefore think the dunes in this image were generated in two earlier climatic phases, different from that of today. (1) During a phase when winds were stronger and dominantly from one direction (the south), major linear sand masses accumulated. (2) Later, when wind strengths declined, the star dunes formed. [Modern-day features known as wind streaks on the edge of the present erg (not shown), are younger than either the linear or star dunes, and show that present-day, sand-moving winds blow from the southwest.]
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To the east and south of the Jungfrau is the Aletsch Glacier, clearly marked by dark medial moraines extending along the glacier’s length parallel to the valley axis. The medial moraines are formed from rock and soil debris collected along the sides of three mountain glaciers located near the Jungfrau and Moench peaks. As these flowing ice masses merge to form the Aletsch Glacier, the debris accumulates in the middle of the glacier and is carried along the flow direction. Lake Brienz to the northwest results from the actions of both glacial ice and the flowing waters of the Aare and Lütschine rivers, and has a maximum depth of 261 meters (856 feet). The lake has a particularly fragile ecosystem, as demonstrated by the almost total collapse of the whitefish population in 1999. Possible causes for the collapse include increased water turbidity associated with upstream hydropower plant operations, and reduction of phosphorus—a key nutrient for lake algae, and a basic element of the local food web—due to water quality changes.
