FYFD

Category: Phenomena

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    Sniffing in Stereo

    Snakes’ forked tongues have long inspired fear, but, in reality, they are part of a highly-effective sensory system. When snakes flick out their tongues, they waggle them up and down about 15 times a second. That motion draws air inward toward the tongue (Image 2), allowing scent molecules to stick to the saliva on either side of the tongue. Once those molecules are gathered, the snake pulls its tongue back into its mouth, where it settles into two grooves (Image 3). Each one has its own path to the snake’s olfactory organs, giving the snake independent spots to evaluate the left and right forks. That means the snake knows which side has a stronger scent and is better able to track its prey. (Video and image credit: Deep Look)

  • Fast-Moving Martian Rivers

    Fast-Moving Martian Rivers

    For the first time, scientists have found evidence of deep, fast-flowing ancient rivers on Mars. After examining images taken recently by the Perseverance rover in Jezero Crater, fluvial experts have spotted familiar signs of turbulent river flow. The mosaic above shows an area nicknamed “Shrinkle Haven,” where curved bands of rock mark the landscape. Although scientists are confident that a powerful river deposited these rocks, they’re still debating whether that river was a meandering one like the Mississippi or a braided river like the Platte.

    Nicknamed "Pinestand," this hill's sedimentary layers were likely formed by a deep fast-moving river.
    Nicknamed “Pinestand,” this hill’s sedimentary layers were likely formed by a deep, fast-moving river.

    In another area, known as “Pinestand,” scientists spotted hills as high as 20 meters tall with clear sedimentary layers. Like Shrinkle Haven’s rock bands, formations like this are most often associated with a large, fast-flowing river. (Image credits: NASA/JPL-Caltech/ASU/MSSS; via Gizmodo; see also NASA JPL)

  • Swirls Over the Canaries

    Swirls Over the Canaries

    Rocky, isolated islands disturb the atmosphere, sending air swirling off one side of the island and then the other. The effects are not always visible to the naked eye, but, as they do here, they can show up in satellite imagery as whirling von Karman vortex streets. The eddies of this image are due to the Canary Islands, and if you follow the line of swirls backward, you’ll find their originating islands. Note that the cloudy swirls don’t appear immediately behind the islands. That’s because there wasn’t enough moisture in the air for clouds to condense yet; the same swirls that you see in the downstream clouds exist in the clear air closer to the islands. (Image credit: A. Nussbaum; via NASA Earth Observatory)

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    The Epic Migration of Plankton

    Zooplankton are tiny creatures found throughout Earth’s oceans. During the daytime, they linger in the twilight depths, where they are harder for predators to spot. But once the sun sets, zooplankton migrate hundreds of meters upward to reach the abundant food near the surface. When sunrise comes, they migrate back downward. Given their size, this feat is astounding; equivalent to a human running two 10-kilometer races a day at Olympic marathon speeds. And, despite their tiny size, these motions leave a mark; researchers have shown that the collective action of all these tiny swimmers is large-scale turbulence with serious mixing potential. (Video and image credit: Be Smart)

  • Liquid Lens Rupture

    Liquid Lens Rupture

    A blob of sunflower oil floating on soapy water forms a disk known as a liquid lens. But add some dyed ethanol and things take a turn. The lens rapidly expands and distorts as the ethanol and soapy water meet. These surface flows are driven by the imbalance of surface tension between the different liquids. The liquid lens deforms and abruptly ruptures, releasing dye and ethanol before rebounding into a stable lens again. Adding more ethanol to the lens will repeat the cycle. (Image credit: C. Kalelkar and P. Dey; research credit: D. Maity et al.)

  • Wave Clouds From Space

    Wave Clouds From Space

    An astronaut snapped this image of wave clouds formed around the Crozet Islands, which lie between South Africa and Antarctica. Clouds like these form when warm, moist air gets pushed up and over a mountain. As it rises, the air cools and its pressure decreases, causing condensation. Pushed out of equilibrium, gravity then pulls the air back downward in the wake of the mountain. That warms the air, causing evaporation. Like a mass bouncing on a spring, the air continues to yo-yo up and down, forming cloudy stripes and clear ones until the energy from its mountain climb is spent. (Image credit: NASA; via NASA Earth Observatory)

  • How Squall Lines Form

    How Squall Lines Form

    Summertime in the middle U.S. means thunderstorms, many of which can form long lines of storms known as squall lines. Complex convective dynamics feed such storms. Here is an illustration of one part of a squall’s lifecycle:

    Illustration of squall line formation.
    As rain falls and evaporates, it fuels the formation of a cold pool of air below the cloud. Incoming wind (gray arrows) blocks the cold pool from spreading. In turn, the cold pool acts as a ramp that redirects this warm, moist air upward. The vertical variation in wind speed (wind shear, shown with pink arrows) creates a positive vorticity. Together with the negative vorticity in the cold pool, this induces a vorticity dipole that lifts air and moisture, feeding the growing line of storms.

    As it falls, rain evaporates, cooling air near the ground and forming a cold pool. If incoming winds block the cold pool from spreading, the pool will act instead as a ramp that redirects the wind upward, carrying any warmth and moisture up into the storm cloud. Wind shear — a vertical variation in wind strength with altitude — creates positve vorticity that opposes the negative vorticity inherent to the cold pool. Together these two regions of opposing vorticity lift more air and moisture into the squall, generating more clouds and more rainfall. (Image credit: top – J. Witkowski, illustration – C. Muller and S. Abramian; see also C. Muller and S. Abramian)

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    EpiPen in Action

    Researchers are hard at work developing needle-free alternatives to injection, but devices like the EpiPen — used in anaphylactic emergencies for food and insect allergies — aren’t going anywhere yet. In this Slow Mo Guys video, they show what happens when an EpiPen fires into ballistic gel.

    An EpiPen’s needle is extremely narrow and about 15 millimeters long. It enters the gel (and presumably the human body) at a modest speed of ~6 m/s, releases the medication, and retracts. Despite its relatively slow speed, the needle is visibly blunted after use (and, no, the EpiPen is not reusable, for this and other reasons).

    Injections like this may be tough for some people to see, but as Dan’s mother attests, they’re absolutely life-saving for the patients that need them. (Video and image credit: The Slow Mo Guys)

  • A Sea of Pollen

    A Sea of Pollen

    Fellow allergy sufferers, beware! This false-color satellite image of the Baltic Sea shows massive slicks made up of pine pollen. I don’t know about you, but the mere thought of enough pollen that it’s visible from space makes me want to double — triple?! — my antihistamines. The swirling patterns in the pollen come from wind-driven currents and waves moving the pollen on the surface of the water.

    It took some sleuthing for scientists to identify these slicks as pollen rather than bacteria or plankton. But by combining experimental results, ground-based observations, and satellite image processing, scientists discovered that the pine pollen has a particular spectral signature. Using that, the team could trawl through older satellite imagery and locate pine pollen in previous seasons. They identified pine pollen slicks in 14 of the last 20 springs. The size of the slicks is growing over time, too, consistent with other observations of longer pollinating seasons. (Image credit: L. Dauphin; via NASA Earth Observatory)

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    Splash-Spread Mushrooms

    Bird’s nest fungi are tiny — only about a centimeter wide. When mature, they form a curved splash cap containing spore sacs known as peridioles. Then they await rain. When a lucky drop hits the mushroom, it flings the peridioles out of their nest. Some will use sticky cords to cling to nearby blades of grass, setting them up to eventually hitch a ride to elsewhere with a grazing herbivore. It’s an impressive journey for a teeny spore sac, and it all starts with a single drop of rain. (Image and video credit: Deep Look)