ISS027-E-5274
Like the Himalayas to the south, the uplift of the Tien Shan results from the ongoing collision between the Eurasian and Indian tectonic plates. The rugged topography of the range is the result of subsequent erosion by water, wind and, in the highest parts of the range, active glaciers. Two types of glaciers are visible in the image; cirque glaciers occupy amphitheater-like depressions on the upper slopes of the mountains, and feed ice downslope to aggregate into large valley glaciers such as the one at image center. Low clouds obscure an adjacent valley and glaciers to the north (upper left).
Two high peaks of the central Tien Shan are identifiable in the image. Xuelian Feng has a summit of 6, 527 meters (21,414 feet) above sea level. To the east, the aptly-named Peak 6231 has a summit 6,231 meters (20,443 feet) above sea level.
ISS027-E-6501
In these astronaut photographs (also see ISS027-E-6500) from the cupola—taken one minute and thirteen seconds apart on March 20, 2011—two distinct cyclonic vortices whirl within an area of low pressure that spanned the Pacific coast from southern California to Vancouver Island. Part of one of the ISS solar arrays also is visible at image upper left in both images.
The vortices indicate the positions of two storm systems located within a broad area of low pressure over the northeastern Pacific Ocean. Through a process known as cyclogenesis, rotating cyclonic weather systems develop, mature, and dissipate along the frontal zones between different air masses (sometimes termed a zone of occlusion). The smaller of the two systems (ISS027-E-6501) displays a dense cloud pattern and arcing band of the cold front extending from the center of a young, maturing cyclone. The diffuse cloud pattern of the larger system (ISS027-E-6500) indicates an older, dissipating system.
ISS027-E-6500
In these astronaut photographs (also see ISS027-E-6501) from the cupola—taken one minute and thirteen seconds apart on March 20, 2011—two distinct cyclonic vortices whirl within an area of low pressure that spanned the Pacific coast from southern California to Vancouver Island. Part of one of the ISS solar arrays also is visible at image upper left in both images.
The vortices indicate the positions of two storm systems located within a broad area of low pressure over the northeastern Pacific Ocean. Through a process known as cyclogenesis, rotating cyclonic weather systems develop, mature, and dissipate along the frontal zones between different air masses (sometimes termed a zone of occlusion). The smaller of the two systems (ISS027-E-6501) displays a dense cloud pattern and arcing band of the cold front extending from the center of a young, maturing cyclone. The diffuse cloud pattern of the larger system (ISS027-E-6500) indicates an older, dissipating system.
ISS027-E-9564
This astronaut photograph illustrates a network of irrigation canals and fields located approximately 42 kilometers (26 miles) to the west-northwest of the city of Gode. Floodplain sediments and soils are dark brown to gray (image center), and contrast with the reddish rocks and soils on the adjacent plateau. Vegetation in the flood plain (image top center) and agricultural fields is dark green.
Water in the Shebelle River and the irrigation canals has a bright, mirror-like appearance due to sunglint, or light reflecting off the water surface back toward the International Space Station. The river water supports a variety of crops—the most common being sorghum and maize—as well as grazing for livestock (cattle, sheep, goats, and camels).
The Shebelle River does not reach the Indian Ocean during most years, but disappears into the sands near the coast in Somalia. During periods of heavy rainfall and flooding however, the Shebelle can reach the Indian Ocean.
ISS027-E-9771
Sunglint is caused by light reflecting off a water surface directly back towards the observer. Variations in the roughness of the water surface—the presence or absence of waves due to wind and currents—will cause differences in the intensity of the sunglint. The presence of other materials, such as oils or surfactants, can also change the properties of the water surface.
In this image, the presence of currents is highlighted as darker patches or streaks (image left and upper right). In contrast, shallow water in the lagoon presents a more uniform, mirror-like appearance, suggesting that there are no subsurface currents. Wave crests visible around the atoll are likely the result of both surface winds and subsurface currents.
Located between the Mozambique coast of Africa and the island of Madagascar, Bassas da India is part of the French Southern and Antarctic Lands. It is uninhabited because it is completely submerged at high tide; there is no vegetation on the atoll for the same reason. The atoll is approximately 10 kilometers (6 miles) in diameter, and covers an area (including the lagoon) of approximately 80 square kilometers (31 square miles).
ISS027-E-12224
While the terminator is often conceptualized as a hard boundary—and is frequently presented as such in graphics and visualizations—in reality the edge of light and dark is diffuse due to the scattering of light by the Earth’s atmosphere. This zone of diffuse lighting is experienced as dusk or twilight on the ground; while the Sun is no longer visible, some illumination is still present due to light scattering over the local horizon.
The terminator is visible in this panoramic view across central South America, looking towards the northeast. An astronaut shot the photo at approximately 7:37 p.m. local time. Layers of the Earth’s atmosphere, colored bright white to deep blue, are visible on the horizon (or limb). The highest cloud tops have a reddish glow due to direct light from the setting Sun, while lower clouds are in twilight.
The Salar de Coipasa, a large salt lake in Bolivia, is dimly visible on the night side of the terminator. The salar provides a geographic reference point for determining the location and viewing orientation of the image.
ISS027-E-11058
The Paraná River ranges up to 3 kilometers wide along the reach illustrated in this image. The main channel is deep enough to allow smaller ocean-going ships to pass north to the capital city of Asunción, Paraguay, fully 1,200 kilometers (745 miles) inland and well out of the image.
The river’s dark brown shading indicates a heavy load of muddy sediment; smaller side channels also carry this mud. Numerous lakes are typical on active floodplains, and appear here as irregular bodies of water. Some appear brown, indicating that they probably have been refilled during recent rises and floods of the active channels.
The Paraná floodplain occupies the entire image; it is so wide—18 kilometers (11 miles) in this view—that its banks are not visible. Numerous curved, meandering channels are the most prominent characteristic of the floodplain, indicating prior positions of the river and its channels. As riverbeds move laterally by natural processes, they leave remnants of their channels, which appear as lakes and finally fill with mud. This is an excellent image for illustrating these meander forms.
From a geological standpoint, it is interesting that almost all of the old channels are similar in curvature to today’s side channels. However, almost none of them seem to show prior positions of the main, wide Paraná channel.
Other astronaut photographs show examples of meandering—on the Rio Negro of southern Argentina, the Mamore River of Bolivia, and the Amazon River of western Brazil.
ISS027-E-16922
While many of the small glacier- and snowmelt-fed streams on the Plateau give rise to major Southeast Asian rivers (including the Mekong and Yangtze), some empty into saline lakes such as Lake Ayakum. This astronaut photograph highlights two river deltas formed along its southwestern shoreline.
When sediments build up to the point that a river can no longer flow over them, the river will jump to a new channel and begin the process anew. Over geologic time, the channels tend to sweep back and forth—similar to the motion of a windshield wiper—to form the semi-circular or fan shape typical of a delta.
Gray to tan surfaces indicate prior positions of the river channels; the uniform coloration and smooth texture suggest that they are relatively old and now inactive. By contrast, the younger and currently active delta surfaces have reddish-brown sediment and visible river channels.
Lateral channel migration is particularly evident in the approximately 8-kilometer (5-mile) wide active delta at image upper left. The reddish color of the fresh sediment may indicate a change from the sources that formed the older parts of the deltas. It might indicate weathering and soil formation on the older deposits. It could even be a sign of episodic inputs of dust or other material to the river catchments.
ISS027-E-27019
Flood waters around Tomato appear confined by an embankment in the west. The embankment extends southward from a bend in the Mississippi. West of the embankment lies a patchwork of agricultural fields. East of the river lies an expanse of dark green forest, the Anderson-Tully State Wildlife Management Area.
ISS027-E-27023
The land cover around the Mississippi in this region is a combination of forest (dark green) and cropland (rectangles of green and brown). Where muddy water has inundated fields, the borders of some fields peek through the water, appearing as green lines. Along the eastern bank of the Mississippi (image center), a double loop pushes away from the river. This long-term feature (not the result of 2011 flooding) is likely transitioning to an oxbow lake.
