Objects moving across the water surface produce a V-shaped pattern, known as the Kelvin Wake pattern. The inside of the V is filled with transverse curved waves, (each of which is an arc of a circle centered at a point lying on the path at a distance twice that of the arc to the wake source) these transversal waves are often obscured by interferences like propeller wash, and tail eddies behind a boat’s stern.
When wood sinks to the bottom of the ocean -shipwrecks, uprooted trees, etc- it is soon colonised by life. Clam-like creatures called Xylophaga chisel through the wood with their own shells and feed off the splinters. Small crustaceans and predatory worms squirm through the wood. Large squat lobsters sit on the surface, tearing strips off the bark with spoon-shaped claws.
It is estimated that 90 percent of these species live nowhere else in the ocean. These marine creatures live only on land plants.
When streams emerge from mountains, they often spread out and deposit sediment in a distinctive pattern known as an alluvial fan.
Alluvial fans in arid areas are often used for agriculture because they are relatively flat and provide groundwater for irrigation, like this one in Kazakhstan’s Almaty province.
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Icebergs are not always uniformly white. Blue stripes are formed as iceberg layers melt and refreeze quickly, while green stripes are created by the freezing of algae-rich sea water. Other coloured stripes, such as black, brown and yellow, were created by sediment collected by the ice as it moved down a hillside towards the sea. As the iceberg melts, it often rotates to expose contrasting layers.
These icebergs may have taken hundreds or even thousands of years to form.
It is not unusual to find ice spheres accumulating along places like the Northeastern shore of Lake Michigan during cold winters. The balls tend to form where water turbulence breaks up a layer of slush. Mattes of slush and frazil ice accrete in the turbulent, supercooled water. Where the wave action is strongest, typically near-shore, slush and frazil evolve into spherical lumps. If conditions are just right, they’ll continue to grow until waves push them ashore.
From Earth Science Picture of the day
Photos by Leda Olmsted
“To conduct pressure tests in a safer manner, a water tank was constructed to encase the fuselage. It was submerged and filled with water, and then additional water was pumped into the cabin until the pressure inside the fuselage reached 1P, the equivalent of flight. This was then cycled to simulate many flights over the life of an aircraft.
By using water instead of air, water being a much less compressible fluid, the test would be much safer and the fuselage would be able to be repaired and re-tested as necessary. Had air been used, the results would have resembled the catastrophic in-flight break-ups at Elba and Naples.”
- Federal Aviation Administration
From the Retronaut
On November 20, 1980, an oil rig accidentally drilled into a salt mine under Lake Peigneur, Louisiana. The lake quickly started to drained into the hole, creating a whirlpool that sucked in the drilling platform, eleven barges and 65 acres (260,000 m2) of the surrounding terrain.
So much water drained into the mine that the flow of the Delcambre Canal that usually empties the lake into the Golf of Mexico was reversed, making the canal a temporary inlet. This backflow created, for a few days, the tallest waterfall in the state of Louisiana as the lake refilled with salt water from the Ocean.
The lake that was once around 6 feet deep is now around 1300 feet deep in places, and turned from fresh water to salt water.
Mayn River, Russia, 2000
The Mayn River is a tributary of the larger Anadyr River, which flows through the far northeastern corner of Siberia. These rivers are frozen for about eight to nine months in a year.
From the NASA “earth as art”
Map of the major endorheic basins of the world. Basins are shown in dark gray, major endorheic lakes are shown in black.
There is one class of water-bodies for which the journey is terminated prior to its surface water reaching the oceans. Such water-bodies exist in closed or endorheic watersheds, which contain rivers or lakes that do not drain to the oceans. The water in these basins may only leave the drainage system by evaporation and seepage.
Lakes in endorheic watersheds are often called “terminal ” or sink lakes.