Month: March 2022

Eruption in a Box
In layers of viscous fluids, lighter and less viscous fluids can displace heavier, more viscous liquids. Here, researchers demonstrate this using four fluids sandwiched between layers of glass and mounted in a rotating frame. (Think of those liquid-air-sand art frames found in museums but bigger!)
In their first example, each layer of fluid is denser than the one beneath it, so buoyancy forces the lowest layer — air — to rise. The air pushes its way through the more viscous layer of olive oil, then slowly makes its way through the even more viscous glycerin before bursting through the last layer in an eruption. As the team varies the viscosity and miscibility of the layers, the movement of the buoyant fluids through the viscous layers changes dramatically. (Image and video credit: A. Albrahim et. al.)
March 31, 2022
Bendable Ice
Ice — as we typically encounter it — is extremely brittle and easily broken. That’s due to defects in the ice, places where atoms have settled into a spot that does not match the perfect crystalline alignment. Because tiny defect-free threads of ice made by researchers turn out to be wildly flexible!
To make these perfect ice strands, each of which is a tiny fraction of the thickness of a human hair, researchers applied an electric voltage to a needle in a water-vapor-filled chamber. The technique condensed ice microfibers with perfect crystal structures in a matter of seconds. When bent, the microfibers actually shift from one crystalline arrangement to another in order to carry stress, and once the force is removed, the thread reverts back to its initial straight form. (Image and research credit: P. Xu et al.; via Science News; submitted by Kam-Yung Soh)
March 30, 2022
Columbia Glacier’s Retreat
In southeastern Alaska, the Columbia Glacier once stretched as far as Heather Island in Prince William Sound. After a long period of stability, the glacier began retreating in 1980 and currently sits more than 15 miles from its previous extent. This video explores the glacier’s evolution through false-color satellite imagery, which allows researchers to distinguish the glacier from sea ice, open water, exposed rocks, and nearby vegetation. Though rapid overall, the glacier’s retreat takes place in fits and starts, due to a combination of influences including climate change, sea and ice interactions, and the effects of local topography. (Video and image credit: NASA Earth Observatory)
False-color animation showing the retreat of Alaska’s Columbia Glacier since 1980.
March 29, 2022
Dissolving Pinnacles
Limestone and other water-soluble rocks sometimes form sharp stone pinnacles like the ones seen here in Borneo. Scientists have recreated these structures in the laboratory simply by immersing water-soluble substances (essentially blocks of candy) into water. Without any background flow, the blocks will slowly form these pinnacle forests as material dissolves into the nearby water, creating a heavy solute-rich fluid that sinks down the exterior of the block. The convection generated by this dissolution drives the material into these sharp shapes, as shown mathematically in this recent study. (Image credit: N. Naim; research credit: J. Huang and N. Moore; via APS Physics)
March 28, 2022
“Oil Paintings”
To capture his images of auroras, nebulas, and comets, photographer Juha Tanhua points his camera lens downward, not upward. Despite their astrophysical appearance, Tanhua’s “oil paintings” are actually parking lot oil spills. The stars are roughened bits of asphalt, and the colors come from thin film interference in a layer of oil (similar to the way colors appear in soap bubbles). It’s amazing how much beauty he captures in examples of urban pollution. (Image credit: J. Tanhua; via Colossal)
March 25, 2022
Erie Ice
Lake Erie, the shallowest of the Great Lakes, sees large swings in ice cover over the winter. In late January 2022, the lake was nearly completely frozen over, with 94 percent of its area covered in ice. By February 3rd, ice cover had dropped to 62 percent before rising again to 90 percent by the 5th. Air temperature and wind are the primary drivers of Erie’s fast ice growth and decay. As storms roll through, the ice can spread rapidly, but once temperatures rise, it takes very little forcing from the wind for the ice to begin breaking up. (Image credit: J. Stevens/USGS; via NASA Earth Observatory)
March 24, 2022
Burning Virtual Forests
Wildfires are growing ever more frequent and more destructive as the climate crisis worsens. Unfortunately, simulating and predicting the course of these fires is incredibly difficult, requiring a combination of ecology, meteorology, combustion science, and more. To handle so many variables, model builders often turn to statistics that allow them to simulate an entire forest but at the cost of representing individual trees as a few pixels or a cone.
In this video, researchers show a new wildfire simulation based on a computationally efficient but more realistic depiction of trees. With individual, three-dimensional trees, the simulation can capture effects that are otherwise hard to examine – like the difference in burn rate for coniferous and deciduous forests and the likelihood that a fire can jump a firebreak of a given size. Their weather, fire, and atmospheric models are even able to simulate the birth of fire-generated clouds! Check out the full video to see more and then head over to their site if you’d like to dig into the methodology. (Video and research credit: T. Hädrich et al.; see also)
March 23, 2022
Tricking a Kettle
Electric kettles are designed to shut off when the water inside them boils. But what does that mean exactly? In this video, Steve Mould explores that question by trying to trick his kettles into boiling off ethanol, a liquid with a lower boiling temperature than water. Steve figures that, if a kettle is designed to shut off at 100 degrees Celsius (water’s boiling point), then it will overboil ethanol since its temperature will never get that high.
I’ll let you watch the video and see what happens…
(more…)
March 22, 2022
Liquid Bridges
In 1893, Baron Armstrong demonstrated a peculiar phenomenon — a liquid bridge of water suspended between two beakers with a strong electric charge between them (Image 1). More than a century later, the details of the mechanism remain challenging to pin down thanks to the setup’s combination of electohydrodynamics, heat transfer (Image 2), evaporation, and chemistry (the electrodes can split water).
Researchers have pinned down a few details, though, like that the break-up of the liquid bridge (Image 3) depends on its effective length and that the effective length grows as applied voltage increases. Researchers also found that inducing an external flow can extend the bridge’s lifetime, though it does not affect the length at which it breaks up. Interestingly, the phenomenon is not limited to water (and its odd chemistry); ethanol and glycerol have been used for liquid bridges, too! (Image and research credit: X. Pan et al.)
March 21, 2022
“Heaven”
Wispy white cirrus clouds cover dark skies glittering with stars in Roman De Giuli’s “Heaven”. Or so it appears. In reality, these skyscapes are made with watercolors, ink, and acrylic paint. The vistas are gorgeous regardless of whether they’re driven by turbulent convection (as in the atmosphere) or the Marangoni effect (as in this video)! (Video and image credit: R. De Giuli)
March 18, 2022