FYFD

Category: Phenomena

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    Chasing Tornadoes

    Tornadoes are some of the most powerful storms on Earth. Their difficult-to-predict nature means that we still have a relatively scant understanding of exactly how they form. We know the conditions that promote their development — warm, moist rising air, wind shear, and rotation — but how and when those translate into a dangerous funnel cloud is harder to pin down. In this video, we hear from one of National Geographic’s storm researchers, Anton Seimon, who chases these storms in search of answers. (Image and video credit: National Geographic)

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    Permeable Pavement

    Controlling storm water is a major challenge in urban environments, where many surfaces are impermeable. In a city, rain cannot simply soak into the ground and filter into the water table. One potential solution is permeable pavement, which uses the same ingredients as its common counterpart minus the sand that usually packs into gaps between the gravel. Without the sand, the final pavement allows water to soak through, as seen above. In practice, the water sinks into a porous reservoir beneath the pavement that helps store and regulate the water’s discharge into the soil.

    Unfortunately, this solution has its limitations. Permeable pavement is not as strong as the regular variety, so it doesn’t work for highly trafficked areas like roadways. It’s also not well-suited to colder areas, where freezing and thawing may disrupt its operation. But it is another tool in engineers’ toolboxes when it comes to keeping urban environments in harmony with nature’s needs. (Image and video credit: Practical Engineering)

  • Kugel Fountains

    Kugel Fountains

    At science museums and tourist attractions around the world, visitors can spin the multi-tonne spheres of kugel fountains with the brush of their hand. The secret of the sphere’s mobility is aquaplaning – the same phenomenon that can cause cars to lose traction in wet conditions. In these fountains, the massive sphere sits in a precisely-shaped cup, with their surfaces separated by a thin layer of water. The entire system acts like a hydrostatic bearing, which allows the sphere to move freely. But even a relatively small disruption can destroy the effect, as happened to the Science Museum of Virginia’s original Grand Kugel after it cracked. (Image credit: E. Roberts; via Atlas Obscura; submitted by Kam-Yung Soh)

  • Rocking From The Waves

    Rocking From The Waves

    Not all seismic activity stems from earthquakes. In fact, much of Earth’s measured seismic waves come from interactions of the ocean and atmosphere with solid ground. Some of the strongest vibrations come from interactions of ocean waves, which transmit pressure waves that don’t attenuate with depth before passing into the solid Earth.

    How those waves propagate and scatter inside the Earth has been a matter of contention for decades, but recent simulations are beginning to uncover the mechanisms that lead to the waves seismologists measure. (Image credit: I. Mingazova; via Physics Today)

  • Following the Flow

    Following the Flow

    In early December 2020, the world’s largest iceberg — roughly 135 km long by 44 km wide — was heading straight for South Georgia Island. Luckily for the island, iceberg A-68A was being carried by ocean surface currents that approach the island before turning sharply southward. The enormous iceberg followed, rotating nearly 90 degrees and drifting away on faster currents.

    Scientists track these large-scale — 50 to 100 km wide — currents using satellites that measure the ocean height. Currents of this size actually generate a measurable tilt to the ocean surface, which scientists measure and use as input into models that estimate the surface currents’ speed and direction. (Image credit: L. Dauphin and J. Stevens; via NASA Earth Observatory)

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    Breaking Bubbles

    What do a nineteenth-century war ship, a sardine-hunting shark, and a viral bottle trick have in common? Cavitation! The phenomenon of cavitation occurs when a fluid is accelerated such that its local pressure drops below the vapor pressure. As a result, bubbles form and then violently collapse, creating shock waves that can damage nearby surfaces or stun prey. Dianna explains — and reveals some cool historical context that was new to me! — in the video above. (Image and video credit: Physics Girl)

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    The Galloping Starfish

    Starfish won’t win any sprints, but they’re actually quite good at moving around as they hunt for prey. Without brains, starfish are led by their feet, which pull in the direction of food they scent. Each foot is connected to what amounts to an internal hydraulic system within the starfish. With a combination of secreted adhesive and pumping, the starfish can trundle along. (Image and video credit: Deep Look)

  • High Tide

    High Tide

    Broad Sound, in eastern Australia, is home to some of the most extreme tidal swings in the world, with more than ten meters difference between high and low tides. The bay’s peculiar geography, along with the topography of nearby reefs, combine to cause the large tides. This color-enhanced satellite image shows the bay at high tide, as phytoplankton and suspended sediments are swept into the bay and around its many islands. The level of detail is just stunning. I particularly love all the von Karman vortex streets visible in the wakes of islands. I count more than a dozen of them! (Image credit: N. Kuring/NASA/USGS; via NASA Earth Observatory)

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    Slow Mo Pulse Jet Engine

    Pulse jet engines rely on their shape to maintain combustion without moving parts. The pressure waves that travel through the engine pump fresh oxygen into the combustion chamber and then ignite it with exhaust remaining from the last cycle. In this Slow Mo Guys video, we get to see that process in action. It’s a pretty neat view of combustion in a working engine, but these guys are definitely not going to win any awards for safety measures. Seriously, don’t try this at home! (Image and video credit: The Slow Mo Guys)

  • Eyes on the Sun

    Eyes on the Sun

    Though it may look like the Eye of Sauron, this image is actually one of our best-ever glimpses of a sunspot. Captured by the Daniel K. Inouye Solar Telescope, this sunspot is larger than our entire planet, yet we can see details as small as 20km across. The dark central region of the image is the sunspot’s umbra, surrounded by the lighter, streakier penumbra. Along the edges of the image, you see a more typical pattern of bright convection cells. Compared to the rest of the sun’s surface, sunspots are cool — about 1,000 K cooler — due to their intense magnetic field flux inhibiting convection. (Image credit: NSO/AURA/NSF; via Bad Astronomer; submitted by Kam-Yung Soh)