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Water ripples: photo by Ron Pieket, 26 January 2009
We try every now and then to bring the world to a stop
So that we can get off or at least have a thought
That is for once our own
But it's no good because forever and quite apart from what anyone anywhere thinks or knows
Ta onta ienai te panta kai menein ouden
Everything flows
τὰ ὄντα ἰέναι τε πάντα καὶ μένειν οὐδέν
"All things move and nothing remains still"
-- attributed to Heraclitus in Plato, Cratylus, 401, d
Wasserwellen: photo by Bin im Garten, 10 August 2009
Troubled water (remous dans le canal des faux ramparts, Cronenbourg, Strasbourg): photo by Dennis.helfer, 17 August 2008
Delta in Rapadalen. Seen from the summit of Skierfe, Lappland, Sweden: photo by jmn.(setrex), 4 July 2007
The delta of the Atchafalaya River on the Gulf of Mexico. View is upriver to the northwest: photo by Arthur Belala, U.S. Army Corps of Engineers, 24 March 1999 (U.S. Army Corps of Engineers Visual Library)
Songhua River, just west of Haerbin, China. Northeastern China’s Songhua River flows northward out of the Changbai Mountains and cuts across the Manchurian Plain before emptying into the Amur River, which separates northeastern China from Russia’s Far East. As China’s northernmost river system, the Songhua is an important artery for transporting agricultural products grown on the plain. On its way, the river flows past Harbin, the capital of China’s Heilongjiang Province, where it is the source of drinking water for several million people. In November 2005, the city faced a water crisis when an explosion at a chemical factory spilled toxic levels of benzene into the Songhua. In late December, the spill reached the Russian city of Khabarovsk. This image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s Terra satellite shows the Songhua River just upstream (west) of the city of Harbin on April 1, 2002. The main stem of the river and its myriad channels appear deep blue, winding from bottom left toward center right. To the west of the river, shallow lakes appear electric blue. The surrounding landscape reveals the Manchurian Plain in shades of brown, crossed by pale lines (roads) and spots (villages and towns).The extreme flatness of the Manchurian Plain has caused the river to meander widely over time. The result of the meandering is that the river is surrounded by a wide plain that is filled with swirls and curves, showing paths the river once took. The plain includes classic features of meandering rivers, such as ox-bow lakes—semi-circular lakes formed when a meander (a wide bend in the river) is cut off from the main channel by river-deposited sediment. Meandering rivers shift their positions across the valley bottom by depositing sediment on the inside of bends while simultaneously eroding the outer banks of the meander bends: image by NASA Earth Observatory, 1 April 2002
Fan-shaped Martian river delta deposit in an unnamed southern hemisphere crater downslope from a large network of channels that apparently drained into over a long period of time billions of years ago: image by Mars Global Surveyor, 13 November 2003 (NASA)
Ganges River Delta, the largest inter-tidal delta in the world. With its extensive mangrove mud flats, swamp vegetation and sand dunes, it is characteristic of many tropical and subtropical coasts. The vegetation cushions the shoreline from wind and wave action while the mangrove trees provide a habitat and food for aquatic and terrestrial plant and animal life. The increasing demand for lumber and firewood is outpacing the natural re-growth of the mangrove trees. Space Shuttle photographs, taken over time, permit monitoring of environmental changes in the delta caused by population pressures, and allows mapping of geological changes caused by shifting distributaries and delta growth. As seen in this photograph, the tributaries and distributaries of the Ganges and Brahmaputra Rivers deposit huge amounts of silt and clay that create a shifting maze of waterways and islands in the Bay of Bengal: photo by NASA, 6 November 1994
A vortex street often occurs when cloud formations over the ocean are disturbed by wind passing over land or another obstacle. In this true-color Moderate Resolution Imaging Spectroradiometer image, marine stratocumulus clouds have arranged themselves in rows, or streets, which are usually parallel to the direction of wind flow. Downwind of obstacles, in this case, the Madeira and Canary Islands off the west African coast, eddies create turbulent patterns called vortex streets: photo by NASA, 5 July 2002
Earth land surface, ocean color, clouds: composite data from June through September 2001: Goddard Space Flight Center image by Reto Stöckl, enhancements by Robert Simmon (NASA)
