As awkward as they look sometimes, insects are amazing fliers. In this video from Ant Lab, we see all kinds of insects taking flight. Some, like the mantis, execute flying leaps to get in the air, whereas weevils begin flapping from a tripod stance. Watching these videos I’m always struck by how flexible insect wings are. They flex far more than I would imagine. And these insects have a lot of excess lift. Just check out that carrion beetle taking off despite being covered in mites! (Image and video credit: Ant Lab)
Jupiter‘s atmosphere remains quite mysterious, due to our limited ability to measure the depths of the gas giant’s clouds. But measurements from the Juno spacecraft are continuing to shape researchers’ understanding of our massive neighbor. By tracking ammonia distributions in Jupiter’s belts and zones, a team has found a series of circulation cells similar to the Ferrel cells of Earth’s midlatitudes.
Unlike the stronger Hadley cells and polar cells, Earth’s Ferrel cells are relatively weak. They’re driven by turbulence and the motion of the circulation cells to the north and south. The Northern and Southern hemispheres each have one Ferrel cell. In contrast, Jupiter — with its larger size and higher rotation rate — boasts eight Ferrel-like cells in each hemisphere! (Image and research credit: K. Duer et al.; via Universe Today; submitted by Kam-Yung Soh)
It may have been 10 years since the BBC filmed the first timelapse of a growing brinicle, but the footage is just as amazing now as it was then! This video gives you the behind-the-scenes story of what it took to capture this natural wonder under the Antarctic ice. It’s incredible to see the shots of sinking brine streaming off the brinicles, too. The difference in density (and thus refractive index) of the brine and the ocean water is substantial enough that your eye can actually pick them out as separate fluids. I once went snorkeling in an area with similarly varied salinity and it was completely bizarre watching everything suddenly go wavy and blurry as I swam. (Image and video credit: BBC)
This short film from artist Thomas Blanchard focuses on carnivorous plants and their prey. These plants — including Venus fly traps, sundews, and pitcher plants — rely on fluids both to attract and capture their prey. Plants like the Venus fly trap build turgor pressure in their cells to move and prop open their leaves. Once triggered, a mechanical release allows the fluid pressure to snap the trap closed. Sweet-smelling fluids invite insects in, only to become nightmarishly difficult to escape once prey try to unstick themselves from the highly viscoelastic liquids. (Video and image credit: T. Blanchard; via Colossal)
With the right application of force, liquids can take on shapes that defy our intuition. Here researchers sandwiched two immiscible oils between glass slides and applied an electric field. Because the two oils have different electrical responses, charges build along the interface between them. These charges lead to non-trivial electrohydrodynamic flows and a multitude of bizarre shapes. They observed polygonal droplets, streaming droplet lattices, and spinning filaments among others. As long as the electric field remains on, the wild behaviors continue; once the field is turned off, the oils relax back to typical, rounded drops. (Image, video, and research credit: G. Raju et al.; via Physics World)
Sometimes experiments don’t work as planned and, instead of answers, they lead to more questions. In this video, we see an experiment looking at an air bubble trapped beneath a cone. It’s the same situation you get by holding a mug upside-down in a sink full of water but with inclined walls. As the cone moves downward, it squeezes the trapped air bubble. A film of air gets pushed along the walls of the cone, eventually forming finger-like bubbles that wrap around the edge of the cone and get entrained into the vortex ring outside the cone.
Clearly, there is some kind of instability that drives the air bubble to form these fingers rather than spreading uniformly. But the big question is which one? Is this a density-driven Rayleigh-Taylor instability caused by air getting pushed into water? Or is it a Saffman-Taylor instability causes by the less viscous air forcing its way into the more viscous water? What do you think? (Image and submission credit: U. Jain)
How does a droplet sinking through an immiscible liquid settle onto a surface? Conventional wisdom suggests that the settling drop will slowly squeeze the ambient fluid film out of the way, form a liquid bridge to the solid beneath, and spread onto the surface. But for some droplets, that’s not how it goes.
While watching a glycerol droplet settle through silicone oil, researchers discovered a new mechanism for wetting. Initially, the silicone oil drained from beneath the drop, as expected. But then the thinning of the film stalled. Tiny bright spots (above) appeared beneath the light and dark interference fringes of the parent drop. These are spots of glycerol, formed when material from the main drop dissolved into the oil and then nucleated onto the solid surface below. Over time, the island-like spots of glycerol grew. Eventually one grew large enough to coalesce with its parent drop (below), causing the glycerol to quickly spread over the solid surface!
Islands of liquid (darker rings) grow beneath a parent drop (brighter rings) until reaching a size where they coalesce, causing the interference fringes to disappear.
The key to this phenomenon seems to be that immiscibility isn’t perfect. Even trace amounts of solubility between the drop and surrounding fluid are enough to allow these islands to form. And once formed, the islands will grow as long as the drop fluid and the solid surface are chemically attractive. (Image, research, and submission credit: S. Borkar and A. Ramachandran; see also Nature Behind the Paper)
Although dunes are usually associated with scorching climates, they can form in any desert, including in the frozen steppes of western Mongolia. This sunrise photo, taken by an astronaut aboard the ISS, shows Ulaagchinii Khar Nuur. The ice-covered Khar Nuur Lake surrounds two islands, Big and Small Avgash, and cold dunes form textured streaks on either side. The low sun angle accentuates the dunes, making every rippling crest clear. (Image credit: NASA; via NASA Earth Observatory)
Waterfalls, fog, and snow wreathe Yosemite in these beautiful winter landscapes by photographer Michael Shainblum. I love how the tendrils of water and mist give you a real sense of the flow, even in still photos. Check out more of Shainblum’s photography on his Instagram and go behind-the-scenes on his Yosemite trip with this video. (Image credit: M. Shainblum; via Colossal)
Despite their round appearance, the droplets you see here are actually shaped like little pancakes. They’re sandwiched inside a Hele-Shaw cell, essentially two plates with a viscous fluid between them. As these droplets fall through the cell, some remain steady and rounded (Image 1), while others experience instabilities (Images 2 and 3). By varying the ratio of the ambient fluid’s viscosity relative to the drop, the authors found two different kinds of breakup. In the first type (Image 2), droplet breakup occurred due to perturbations inside the drop itself. In the second type (Image 3), the viscosity of the ambient fluid is closer to that of the drop and intrusions of the ambient fluid into the drop break it apart. (Image and research credit: C. Toupoint et al.)
