FYFD

Category: Phenomena

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    Moths and Beetles in Flight

    Watching insects take flight in high-speed video is always mesmerizing. So often their wings look too small and fragile to lift their bulbous bodies, but they manage the feat easily. I especially like to watch how much their wings flex during each up- and downstroke. So often we think that stiffer wings — like those on airplanes — are better for flight, yet nature demonstrates at so many sizes that flexibility is better, especially in flapping flight. A flexible wing can maximize lift in the downstroke and curl to minimize drag on the upstroke. Even wings that fold away, as many beetle wings do, can do the job of lifting an insect once shaken out. (Image and video credit: Ant Lab)

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    Chemical Flowers

    These “flowers” blossom as two injected chemicals react in the narrow space between two transparent plates. The chemical reaction produces a darker ring that develops a streaky outer edge due to competition between convection and chemical diffusion.

    To show how gravity affects the instability, the researchers repeated the experiment on a parabolic flight. In microgravity conditions, no instability formed. That’s exactly what we’d expect if convection (i.e. flow due to density differences) is a major cause. No gravity = no convection. In contrast, under hypergravity conditions, the instability was initially spotty before developing streaks. (Image and video credit: Y. Stergiou et al.)

  • Summer Melt

    Summer Melt

    A warm summer in 2022 has resulted in record melting on Svalbard. Located halfway between the Norwegian mainland and the North Pole, more than half of Svalbard is normally covered in ice. But with glaciers in retreat and firn — a surface layer of compressed porous snow — melting, pale blue ice is getting direct exposure to the sun and warm air temperatures. The result has been melting 3.5 times larger than the average melt between 1981 and 2010. Look closely and you’ll find deep blue meltwater ponds dotting the ice, too. The run-off of meltwater has likely carried extra sediment into the surrounding waters, accounting for some of the paler water colors along the coast. (Image credit: J. Stevens/USGS; via NASA Earth Observatory)

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    Fire Ant Rafts

    When you run into a fire ant, you’re in for a bad day. But if you run into a colony-sized raft of fire ants, well, that’s going to be a very bad day. These insects evolved to survive Amazonian floods, and that prowess has helped them spread far from their original homes. When waters start rushing into their home, the ants set out on a rescue mission, pulling their young out. The ants lash themselves and the youngsters together with their own bodies and form a floating raft. Thanks to the hydrophobic hairs on the larvae and ants, they trap a layer of air near their bodies. This helps them breathe, even if they’re on the bottom of the raft. Learn lots more about fire ants, including how they act as fluid, over here. (Image and video credit: Deep Look)

  • “Keeping Our Sheet Together”

    “Keeping Our Sheet Together”

    When two liquid jets collide, they form a falling liquid sheet. Here researchers explore how that sheet breaks up when the liquids involved contain polymers. The intact areas of the sheet show as dark red or almost black. The edges of the sheet appear in brighter red and yellow, outlining the holes that form and grow during breakup. The type of breakup observed depends on the concentration of polymer in the liquid. (Image credit: C. Galvin et al.)

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    Pistol Shrimp Snaps

    Gram for gram, few animals can match the power of a pistol shrimp’s snap. When its claw closes, the shrimp ejects a jet of water so fast that the water pressure drops below the vapor pressure, causing a cavitation bubble. Like other cavitation bubbles, this one is short-lived, growing and collapsing (and sending out shock waves!) in less than a millisecond. That’s enough to knock any predator or prey for a loop. (Image and video credit: Ant Lab)

  • Jupiter’s Frosted Clouds

    Jupiter’s Frosted Clouds

    This 3D rendering of Jupiter's cloud tops is based on flyby data from the JunoCam instrument. It's not a true physical image of the cloud tops, though scientists are working on a calibration for that. Instead, the elevations shown here are based on the intensity of visible light registered by the instrument. This measure correlates with cloud height, but there are exceptions.
    This 3D rendering of Jupiter’s cloud tops is based on flyby data from the JunoCam instrument. It’s not a true physical image of the cloud tops, though scientists are working on a calibration for that. Instead, the elevations shown here are based on the intensity of visible light registered by the instrument. This measure correlates with cloud height, but there are exceptions.

    New 3D renderings of Jovian clouds show textured swirls akin to a cupcake’s sculpted frosting. The images are based on flyby data from the JunoCam instrument. Because illumination of the clouds is generally brightest for the highest clouds, the team has rendered elevation based on brightest. While this is somewhat physical, it’s not exactly what Jupiter looks like. For that, Juno scientists are working on a calibration that will translate these initial renderings into a truer physical model. Nevertheless, the results are stunning, especially the flyover video embedded over here! (Image credit: 3D renders – NASA / JPL-Caltech / SwRI / MSSS / G. Eichstädt, image pair – G. Eichstädt et al.; via phys.org; submitted by Kam-Yung Soh)

    Cross your eyes to see this image pair as a 3D image of Jupiter's cloud tops.
    Cross your eyes to see this image pair as a 3D image of Jupiter’s cloud tops. The brighter regions will appear closer than the darker ones.
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    How Gas Pump Nozzles Work

    Ever wonder how a gas pump shuts off when the tank is full? You might guess that there’s a sophisticated electronic sensor hidden in there. But there isn’t! Gas pumps use an entirely mechanical technique to sense a full tank and shut off flow, as Steve Mould demonstrates in this video.

    There are two key components — one fluid mechanical and one based on mechanical linkages — inside the handle. The part that senses a full tank is a Venturi tube, shown in Image 2. The top section of the Venturi tube contains a constriction, where (incompressible) flow is forced to speed up. That increase in speed creates a drop in pressure, which is reflected by the movement of the water in the curved tube below the constriction.

    Notice that when there’s no flow through the top tube, the water level is equal on either side of the lower, curved tube. That means that the outside air pressure (connected to the short arm) equals the pressure in the constriction (connected to the long arm). When air is flowing through the constriction, the water level shifts. The water in the short arm gets pushed down while the water in the long arm gets sucked up. That change means that the air pressure outside the tube is now higher than pressure in the constriction.

    I’ll let Steve explain what that means for the gas pump! (Image and video credit: S. Mould)

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    Leaky Resonance

    Some resonators aren’t perfect — nor are they meant to be! Here, researchers experiment with resonance using a disk shaking up and down over a pool of water. The disk never touches the water, but its movement makes the air above the water move in and out, like a miniature, changeable wind. The air flow distorts the water surface, creating waves just tens of microns high. Beneath the disk, the water forms standing waves, indicating resonance.

    But the waves don’t stay under the disk. Beyond its edge, we see traveling waves moving outward, carrying some of the disk’s energy with them. This leakage is actually how many musical instruments, like a guitar, work. When the guitar strings are plucked, their vibrations are transmitted into the body of the guitar through its bridge, where the strings are anchored. The body acts as a resonator, amplifying the sound, some of which leaks out the sound hole. (Image and video credit: U. Jain et al.)

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    Dolphins Playing With Bubble Rings

    Blow a jet of air underwater and you can make a bubble ring. It takes some practice for humans, or you can use a device. In this video, a team introduced wild dolphins to a bubble-ring-making machine and observed how the dolphins reacted. After some initial wariness, the animals played with them for hours, creating games and having fun. Note that there are some dolphins who create their own bubble rings to play with, so it’s hard to say that these particular dolphins have never seen a bubble ring before. But even if they have seen the bubbles, they wouldn’t have seen a machine making them. (Image and video credit: BBC Earth)