FYFD

Tag: science

  • The Underwater Effects of Volcanoes

    The Underwater Effects of Volcanoes

    Although volcanoes are typically located in or near the ocean, we’ve spent relatively little effort studying how eruptions affect the marine environment. A recent research voyage aimed to change that by studying the Patagonian Sea near the site of the 2008 Chaitén eruption. Marked by massive ashfalls that, when mixed with heavy rains, created huge mudslides, the 2008 eruption was the Chaitén volcano’s first in 9,000 years.

    The researchers mapped the seafloor near the volcano, finding massive dunes shaped by strong currents. Using a remotely operated vehicle, the team surveyed and sampled the seafloor, collecting sediments reaching back some 15,000 years. They also located ash from the 2008 eruption over 24 kilometers from the volcano. With their data, they hope to understand both how the recent eruption changed the marine environment as well as how older eruptions affected the area. (Image credits: volcano – USGS, dunes – Schmidt Ocean Institute; see also Schmidt Ocean Institute; via Ars Technica)

    Composite image showing the massive underwater dunes off the coast.
    Composite image showing the massive underwater dunes off the coast.

    P.S. – This Friday, January 24th from 12 to 1:30pm Eastern I’m moderating a panel discussion on the Traveling Gallery of Fluid Motion and how art and science can work together in public outreach. Register here to join. It’s free!

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  • Swimming Like a Ray

    Swimming Like a Ray

    Manta rays are amazing and efficient swimmers — a necessity for any large animal that survives on tiny plankton. Researchers have built a new soft robot inspired by swimming mantas. Like its biological inspiration, the robot flaps its pectoral fins much as bird flaps its wings; this motion creates vortices that push water behind the robot, propelling it forward. For a downstroke, air inflates the robot’s body cavity, pushing the fins downward. When that air is released, its fins snap back up. With this simple and energy efficient stroke, researchers are able to control the robot’s swimming speed and depth, allowing it to maneuver around obstacles. Flapping faster helps the robot surface, and slower flapping allows it to sink. (Living manta rays also sink if they slow down.) Check out the robot in action below. (Image credit: J. Lanoy; video and research credit: H. Qing et al.; via Ars Technica)

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    The Mystery of the Binary Droplet

    What goes on inside an evaporating droplet made up of more than one fluid? This is a perennially fascinating question with lots of permutations. In this one, researchers observed water-poor spots forming around the edges of an evaporating drop, almost as if the two chemicals within the drop are physically separating from one another (scientifically speaking, “undergoing phase separation“). To find out if this was really the case, they put particles into the drop and observed their behavior as the drop evaporated. What they found is that this is a flow behavior, not a phase one. The high concentration of hexanediol near the edge of the drop changes the value of surface tension between the center and edge of the drop. And that change is non-monotonic, meaning that there’s a minimum in the surface tension partway along the drop’s radius. That surface tension minimum is what creates the separated regions of flow. (Video and image credit: P. Dekker et al.; research pre-print: C. Diddens et al.)

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    Within a Drop

    In this macro video, various chemical reactions swirl inside a single dangling droplet. Despite its tiny size, quite a lot can go on in a drop like this. Both the injection of chemicals and the chemical reactions themselves can cause the flows we see here. Surface tension variations and capillary waves on the exterior of the drop can play a role, too. Just because a flow is tiny doesn’t mean it’s simple. (Video and image credit: B. Pleyer; via Nikon Small World in Motion)

    Chemical reactions swirl within a single, hanging droplet.
    Chemical reactions swirl within a single, hanging droplet.
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  • Why Icy Giants Have Strange Magnetic Fields

    Why Icy Giants Have Strange Magnetic Fields

    When Voyager 2 visited Uranus and Neptune, scientists were puzzled by the icy giants’ disorderly magnetic fields. Contrary to expectations, neither planet had a well-defined north and south magnetic pole, indicating that the planets’ thick, icy interiors must not convect the way Earth’s mantle does. Years later, other researchers suggested that the icy giants’ magnetic fields could come from a single thin, convecting layer in the planet, but how that would look remained unclear. Now a scientist thinks he has an answer.

    When simulating a mixture of water, methane, and ammonia under icy giant temperature and pressure conditions, he saw the chemicals split themselves into two layers — a water-hydrogen mix capable of convection and a hydrocarbon-rich, stagnant lower layer. Such phase separation, he argues, matches both the icy giants’ gravitational fields and their odd magnetic fields. To test whether the model holds up, we’ll need another spacecraft — one equipped with a Doppler imager — to visit Uranus and/or Neptune to measure the predicted layers firsthand. (Image credit: NASA; research credit: B. Militzer; via Physics World)

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  • Blooming in Blue

    Blooming in Blue

    Summers in the Barents Sea — a shallow region off the northern coasts of Norway and Russia — trigger phytoplankton blooms like the one in this satellite image. The blue shade of the bloom suggests the work of coccolithophores, a type of plankton armored in white calcium carbonate. This type of plankton thrives in the warm, stratified waters of the late summer. Earlier in the year, the water tends to be nutrient-rich and well-mixed, conditions which favor diatom plankton species instead. Their blooms appear greener in satellite images. (Image credit: W. Liang; via NASA Earth Observatory)

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  • Tracking Coastal Sediment Loss

    Tracking Coastal Sediment Loss

    Shorelines rely on an influx of sediment to counter what’s lost to erosion by waves and currents. But tracking that sediment flux is challenging in coastal regions where salt, waves, and storms batter delicate instruments. Instead, researchers have turned to remote sensing through high-resolution satellites like Landsat to monitor these areas. Researchers built an algorithm to analyze coastal imagery, validated with local sediment measurements; once built, they deployed it in a free tool that lets anyone build a 40-year timeline of a coastal area’s sediment history.

    Looking at thousands of sites around the world, the team found coastal sediment is on the decline, especially along sandy and muddy coastlines. Where has the sediment gone? It’s likely that human-built infrastructure — both on coasts and upstream along rivers — is disrupting the natural flow of sediments that would replenish these regions. (Image credit: NASA; research credit: W. Teng et al.; via Eos)

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    Cavitation Near Soft Surfaces

    Collapsing cavitation bubbles are sometimes used to break up kidney stones, and they may find other uses in medicine as well. Here, researchers investigate the collapse of laser-triggered cavitation bubbles near tissue-mimicking hydrogel. The bubbles take on a very different form than they do near solid surfaces. Near hydrogel, the bubbles become mushroom-shaped. During their collapse, they release a rainy microjet that moves at nearly 2,000 meters per second! Even at 5 million frames per second, the jet is practically a blink-and-you-miss-it phenomenon. (Image and video credit: D. Preso et al.)

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  • Strata of Starlings

    Strata of Starlings

    Starlings come together in groups of up to thousands of birds for the protection of numbers. These flocks form spellbinding, undulating masses known as murmurations, where the movement of individual starlings sends waves spreading from neighbor to neighbor through the group. One bird’s effort to dodge a hawk triggers a giant, spreading ripple in the flock.

    To capture the flowing nature of the murmuration, photographer and scientist Kathryn Cooper layers multiple images of the starlings atop one another. The birds themselves become pathlines marking the murmuration’s motion. The final images are surprisingly varied in form. Some flocks resemble a downpour of rain; others the dangling branches of a tree. (Image credit: K. Cooper; via Colossal)

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  • Tracking Tonga’s Boom

    Tracking Tonga’s Boom

    When the Hunga Tonga-Hunga Ha’apai volcano erupted in January 2022, its effects were felt — and heard — thousands of kilometers away. A new study analyzes crowdsourced data (largely from Aotearoa New Zealand) to estimate the audible impact of the eruption. The researchers found that the volume, arrival time, and nature of the rolling rumble reported by survey takers correlated well with seismic measurements. But humans provided data that monitoring equipment couldn’t. For example, reports of shaking buildings and rattling windows let researchers estimate the shock wave‘s overpressure far from the volcano. The team suggests that acting quickly to collect human impressions of rare events like this one can add valuable data that’s otherwise overlooked. (Image credit: NASA; research credit: M. Clive et al.; via Gizmodo)