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Tag: science

  • Trapped in a Taylor Column

    Trapped in a Taylor Column

    The world’s largest iceberg, A23a, is stuck. It’s not beached; there are a thousand meters or more of water beneath it. But thanks to a quirk of the Earth’s rotation, combined with underwater topology, A23a is stuck in place, spinning slowly for the foreseeable future. A23a is trapped in what’s known as a Taylor column, a rotating column of fluid that forms above submerged objects in a rotating flow. You can see the same dynamics in a simple tabletop tank.

    Pirie Bank sticks up from the seafloor, which sets up a stationary column of rotating water that iceberg A23a is now stuck in.
    Pirie Bank sticks up from the seafloor, which sets up a stationary column of rotating water that iceberg A23a is now stuck in.

    When a tank (or planet) is rotating steadily, there’s little variation in flow with depth. With an obstacle at the deepest layer — in this case, an underwater rise known as the Pirie Bank — water cannot pass through that lowest layer. And that deflection extends to all the layers above. The water above Pirie Bank just stays there, as if the entire column is an independent object. Caught inside this region, A23a will remain imprisoned there. How long will that last? There’s no way to know for sure, but a scientific buoy in another nearby Taylor column has been hanging out there for 4 years and counting. (Image credit: A23a – D. Fox/BAS, diagram – IBSCO/NASA; via BBC News; submitted by Anne R.)

  • How a Storm Can Ruin Your Tea

    How a Storm Can Ruin Your Tea

    Last November, a windstorm, known as Storm Ciarán in the U.K., blew through Europe with wind speeds as high as 130 kilometers per hour. All that wind came with a significant drop in atmospheric pressure. Researchers found that the pressure drop was large enough to lower the boiling point of water more than full 2 degrees Celsius. That difference probably wouldn’t register for anyone waiting for their kettle to boil, but it could decidedly affect the final cup of tea. Tea flavor is quite sensitive to the temperature of the boiling water used to brew it, as it affects how well the tannins get extracted. According to the researchers, Ciarán’s conditions potentially ruined millions of cups of breakfast tea in the greater London area. (Image credit: E. Akyurt; research credit: G. Harrison et al.; via Gizmodo)

  • The Solar Corona in Detail

    The Solar Corona in Detail

    The sun’s corona — its outer atmosphere — is usually impossible to see, since it’s far outshone by the rest of the sun. But during a total solar eclipse, the moon blocks out all but the vibrant, wispy corona. Getting a detailed image of the corona is tough; it’s constantly shifting. For this image, engineer Phil Hart used 5 main cameras, 4 refractors, 2 laptops, and plenty of digital image processing to capture some incredible details of the plasma and hot gases dancing along the sun’s magnetic field lines. You can learn about the awesome effort behind this image — and see more awesome photos from the eclipse — at his site. (Image credit: P. Hart; via APOD)

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    “Aquakosmos – Ch. 2”

    Colored inks bulge and billow around flowers in filmmaker Christopher Dormoy’s “Aquakosmos – Ch. 2”. Because ink is denser than the surrounding water, it sinks, forming mushroom-like shapes as the Rayleigh-Taylor instability takes over. One of the fun things about this particular video is that we see the Rayleigh-Taylor instability at many different sizes, depending on the size and speed of different falling dyes. (Video and image credit: C. Dormoy)

  • Waves Lap on Titan’s Shores

    Waves Lap on Titan’s Shores

    Titan, one of Saturn’s moons, is the only other planetary body known to have liquid lakes, rivers, and seas at its surface. Whether those bodies — made up of hydrocarbons rather than water, like here on Earth — have waves is a matter of ongoing debate. What data we have from visiting spacecraft is inconclusive. So a group of researchers decided to look for the effects of wave action instead.

    Beginning with a model of flooded areas similar to Titan’s, the team simulated a coastline’s erosion assuming three different situations: 1) no coastal erosion, 2) erosion from waves, and 3) uniform erosion through dissolution. Each set of conditions resulted in a very different final coastline. But, of the three, the wave-eroded coast was most similar to those seen on Titan. That’s a good indicator that, even if our spacecraft couldn’t see waves on Titan, they’re likely there. (Image credit: ESA; research credit: R. Palermo et al.; via Gizmodo)

  • Sediment Swirls

    Sediment Swirls

    Turbulent flows feature swirling eddies over a range of sizes — the larger the size range, the higher the Reynolds number. In this satellite image, sediment highlights these eddies in shades of turquoise, showing off the complexity of the flows created where rivers, ocean, and tides meet. The eddies we see here stretch from kilometers in width down to a handful of meters, but the flow’s turbulence persists down to millimeter-scales before viscosity damps it out. (Image credit: L. Dauphin; via NASA Earth Observatory)

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  • Why Tornado Alley is North American

    Why Tornado Alley is North American

    Growing up in northwest Arkansas, I spent my share of summer nights sheltering from tornadoes. Central North America — colloquially known as Tornado Alley — is especially prone to violent thunderstorms and accompanying tornadoes. That’s due, in part, to two geographical features: the Rocky Mountains and the Gulf of Mexico. Trade winds hitting the eastern slope of the Rockies get turned northward, imparting a counterclockwise vorticity. At the same time, warm moist air carried from the Gulf feeds into the atmosphere, creating perfect conditions for powerful thunderstorms. By this logic, though, South America should see lots of tornadoes, too, courtesy of the Andes Mountains and the moist environs of the Amazon Basin. To understand why South America doesn’t have a Tornado Alley, researchers used global weather models to investigate alternate North and South Americas.

    They found that smoothness is a key ingredient for the upstream, moisture-generating region. Compared to the Amazon, the Gulf of Mexico is incredibly flat. With a flat Gulf, tornadoes abounded in North America, but their numbers dropped once that area was roughened to mimic the Amazon. The opposite held true, too: a smoothed-out Amazon Basin resulted in more simulated South American tornadoes.

    For those in Tornado Alley, the results don’t offer much hope for mitigating our summer storms — we can’t exactly roughen the ocean. But the study does sound a word for warning for South America; the smoother the Amazon region becomes — due to mass deforestation — the more likely tornadoes become in parts of South America. (Image credit: G. Johnson; research credit: F. Li et al.; via Physics World)

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    Toying With Density and Miscibility

    Steve Mould opens this video with a classic physics toy that uses materials of different densities as a brainteaser. Two transparent, immiscible liquids fill the container, along with beads of a couple different densities. When you shake the toy, the liquids emulsify, creating a layer with an intermediate density. As the two liquids separate, the emulsified middle layer disappears, causing the beads (which have densities between that of the two original liquids) to come together.

    The rest of the video describes the challenges of expanding this set-up into three immiscible liquids and four sets of beads. Along the way, Steve had to contend with issues of miscibility, refractive index, and even chemical solvents. It’s amazing, sometimes, what it takes to make a seemingly simple idea into reality. (Video and image credit: S. Mould)

  • Paris 2024: Diving

    Paris 2024: Diving

    In competition diving, athletes chase a rip entry, the nearly splash-less dive that sounds like paper tearing. Part of a successful rip dive comes in the impact, where divers try to open a small air cavity with their hands that their entire body then enters. But the other key component happens below the surface, where divers bend at the hips once underwater. This maneuver enlarges the air cavity underwater and disrupts the formation of a jet that would typically shoot back upwards. Done properly, the result is an entry with little to no splash at the surface and a panel full of pleased judges. (Image credits: top – A. Pretty/Getty Images, other – E. Gregorio; research credit: E. Gregorio et al.; via Science News; submitted by Kam-Yung Soh)

    Sequence of images showing a synthetic diver bending underwater to disrupt splash formation.
    Sequence of images showing a synthetic diver bending underwater to disrupt splash formation.

    Related topics: Rip entry physics, how pelicans dive safely, and how boobies plunge dive

    This post marks the end of our Olympic coverage for this year’s Games, but if you missed any previous entries, you can find them all here.

  • Paris 2024: Clearing the Air

    Paris 2024: Clearing the Air

    A quartet of mushroom-shaped structures tower nearly 6 meters above the Olympic Village. Known as Aerophiltres, these devices filter particulates out of the air to provide cleaner air for the Village, despite its proximity to major roadways. There’s no need to change out the filters in the Aerophiltres, though, because they don’t have any. Instead, the devices ionize fine particles, encourage them to clump together, and then capture them on highly-charged metal plates. A fan near the base sucks polluted air in through the top and expels clean air at the ground level. According to the engineers, the system is capable of removing 95% of particulates and producing nine Olympic-sized swimming pools’ worth of clean air each hour. Compared to traditional systems — which require lots of power to suck air through filters that get progressively more clogged — the Aerophiltres are energy efficient, highly effective, and easy to maintain. (Image credit: SOLIDEO/C. Badet; via DirectIndustry)

    Related topics: How manta rays filter without clogging, making artificial snow, and building whitewater rafting courses

    Catch our past and ongoing Olympic coverage here.