FYFD

Category: Phenomena

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    The Noisy Gluggle Jug

    The fish-shaped Gluggle Jug makes an impressive set of sounds when tilted for pouring. Steve Mould explores their origin in this video. When liquid is poured from a container, air needs a path in to replace the poured liquid. You’re likely most familiar with this from long-necked bottles, where trying to pour the liquid too quickly results in a glug-glug noise as air bubbles periodically force their way through the bottle neck. The same thing happens in the Gluggle Jug, particularly at the joint between the tail and body of the pitcher. The volume and resonance of the jug’s sounds comes from the shape; the open mouth of the container amplifies the sound of bubbles popping back from the tail region. (Image and video credit: S. Mould)

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    Pressure At The Dam

    Hydrostatic pressure in a fluid is based on the fluid’s depth. You’ll rarely see a more dramatic example of that power than with a water release from a dam. Here we see the outlet of the Verbund Hydro Power dam in Austria. With 190 meters of water behind the dam, the outlet jet is massive. It moves 20,000 liters of water per second at a speed of 50 meters per second. Imagine what it would be like to stand next to that! (Image and video credit: Discovery UK; submitted by Olwyn B.)

  • Zuiderzee Works

    Zuiderzee Works

    Few countries have to contend with water the way the Netherlands does. With 26% of its area and 21% of its population living below sea level, water control is critical. This satellite image shows some of the natural and manmade features that help protect the landscape. The West Frisian Islands, the long spine-like archipelago seen here, form the first barrier. Behind them lies the mudflats of the Wadden Sea, home to countless wetland species. The Wadden Sea is separated from the freshwater Lake Ijssel by the Afsluitdijk, constructed in 1932 to protect the country from rising seas. With the dam in place, the Dutch used wind power to drain the shallow lands behind the dam, reclaiming the polders labeled here. With the islands, mudflats, and lake between urban settlements and the sea, engineers have more options for diverting water and protecting people from disastrous flooding. (Image credit: A. Holmes/NASA’s Ocean Color Web; via NASA Earth Observatory)

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    How Sinkholes Form

    Growing up in the Ozarks, I explored my fair share of caves and sinkholes. These geological features form when flowing groundwater erodes soil, sand, and even rock underground. The Ozark Plateau consists largely of limestone, which is water soluble, making it very prone to this internal erosion. As bedrock dissolves away, it is eventually unable to hold up the weight of ground above it, causing a catastrophic collapse into a sinkhole. Although my childhood sinkholes were naturally occurring, they can also form in spots where leaking pipes and infrastructure help wash underlying soil away. Unfortunately for engineers, this internal erosion can take place for years without any visible sign above ground. (Image and video credit: Practical Engineering)

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    Starlings Over Rome

    Each winter millions of starlings migrate to Rome, where they form enormous murmurations in the sky above. The ephemeral and amorphous displays are driven by each bird responding to its neighbor’s motions. But the slight delay in individual responses gives the flock as a whole a wave-like, fluid appearance. Behaviors like this help protect the starlings from predators while they search out places to roost.

    As neat as the displays are, though, they come with some real downsides, as the latter part of this video reveals. I don’t know about you, but I wouldn’t want to park my car outside in that storm! (Video credit: BBC Earth)

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    Really, Really Slow Mo Fluids

    Fluid dynamics is a perfect subject for high-speed video. So much goes on at speeds that are far too quick for our eyes and brains to perceive. But there is such a thing as too slow – a concept explored in this Slow Mo Guys video, which takes everyday activities like turning on a faucet or splashing into a pool and slows them down a speed where one second lasts an hour. The video I’ve embedded here isn’t nearly that long; it speeds up and slows down. But if you really want to, you can watch Gav fall into a pool for a full hour. (Image and video credit: The Slow Mo Guys)

  • Noctilucent Clouds

    Noctilucent Clouds

    Noctilucent clouds are the “highest, driest, coldest, and rarest clouds on Earth.” Formed in the mesosphere at altitudes over 80 kilometers, these clouds typically form at polar latitudes where they can catch sunlight hours after sunset, hence their night-shining name. The clouds take shape when water vapor in cold mesospheric air layers freezes onto dust left behind by meteors.

    Fun fact: because of their high altitude and particle size and density, noctilucent clouds were considered a hazard for space shuttle reentry, and planners explicitly avoided trajectories that would take the spacecraft near potential clouds. (Image credit: top – N. Fewings, other – J. Stevens/NASA Earth Observatory)

    Satellite image of noctilucent clouds above the North Pole.
  • Cleaning Up Combustion

    Cleaning Up Combustion

    In space, flames behave quite differently than we’re used to on Earth. Without gravity, flames are spherical; there are no hot gases rising to create a teardrop-shaped, flickering flame. In many ways, removing gravity makes combustion simpler to study and allows scientists to focus on fundamental behaviors. It’s no surprise, then, that combustion experiments are a long-standing feature on the International Space Station.

    In the photo above, we see a flame in microgravity studded with bright yellow spots of soot. Soot is a by-product of incomplete combustion; it’s essentially unburned leftovers from the chemical reaction between fuel and oxygen. In this experiment, researchers were studying how much soot is produced under different burning conditions, work that will help design flames that burn more cleanly in the future. (Image and video credit: NASA; submitted by @LordDewi)

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    “Feeding the Sea”

    It’s impressive when a microscopic organism is visible from space, but that’s a regular occurrence for phytoplankton, the tiny marine algae that feed much of the ocean. In this video from NASA Earth Observatory, we travel around the globe, observing phytoplankton blooms and learning about the ecosystems they feed — or destroy.

    Note that many of these satellite images have been color-enhanced to bring out the swirls and eddies of each bloom. The colors are enhanced but the patterns are real. (Image and video credit: NASA Earth Observatory)

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    Sandsculpting Bees

    Building sandcastles is more than a pastime for the bumblebee-mimic digger bee. This species of bee collects water into an abdominal pouch, then uses it to wet sand to help her sculpt her nest. She’ll use the material she digs out to create a protective turret over the nest’s entrance, and once her eggs are laid and stocked with food, she’ll deconstruct the turret to rebury the nest and keep her brood safely hidden. (Image and video credit: Deep Look)