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Tag: ice

  • Ice Discs Surf on Herringbones

    Ice Discs Surf on Herringbones

    Inspired by the roaming rocks of Death Valley, researchers went looking for ways to make ice discs self-propel. Leidenfrost droplets can self-propel on herringbone-etched surfaces, so the team used them here, as well. On hydrophilic herringbones, they found that meltwater from the ice disc would fill the channels and drag the ice along with it.

    But on hydrophobic herringbone surfaces, the ice disc instead attached to the crest of the ridges and stayed in place–until enough of the ice melted. Then the disc would detach and slingshot (as shown above) along the herringbones. This self-propulsion, they discovered, came from the asymmetry of the meltwater; because different parts of the puddle had different curvature, it changed the amount of force surface tension exerted on the ice. Thus, when freed, the ice disc tried to re-center itself on the puddle.

    The team is especially interested in how effects like this could make ice remove itself from a surface. After all, it requires much less energy to partially melt some ice than it does to completely melt it. (Image and research credit: J. Tapochik et al.; via Ars Technica)

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    How Particles Affect Melting Ice

    When ice melts in salt water, there’s an upward flow along the ice caused by the difference in density. But most ice in nature is not purely water. What happens when there are particles trapped in the ice? That’s the question this video asks. The answer turns out to be relatively complex, but the researchers do a nice job of stepping viewers through their logic.

    Large particles tend to fall off one-by-one, which doesn’t really affect the buoyant upward flow along the ice. In contrast, smaller particles fall downward in a plume that completely overwhelms the buoyant flow. That strong downward flow makes the ice ablate even faster. (Video and image credit: S. Bootsma et al.)

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  • “Visions in Ice”

    “Visions in Ice”

    The glittering blue interior of an ice cave sparkles in this award-winning image by photographer Yasmin Namini. The cave is underneath Iceland’s Vatnajokull Glacier. Notice the deep scallops carved into the lower wall. This shape is common in melting and dissolution processes. It is unavoidable for flat surfaces exposed to a melting/dissolving flow. (Image credit: Y. Namini/WNPA; via Colossal)

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  • Slipping Ice Streams

    Slipping Ice Streams

    The Northeast Greenland Ice Stream provides about 12% of the island’s annual ice discharge, and so far, models cannot accurately capture just how quickly the ice moves. Researchers deployed a fiber-optic cable into a borehole and set explosive charges on the ice to capture images of its interior through seismology. But in the process, they measured seismic events that didn’t correspond to the team’s charges.

    Instead, the researchers identified the signals as small, cascading icequakes that were undetectable from the surface. The quakes were signs of ice locally sticking and slipping — a failure mode that current models don’t capture. Moreover, the team was able to isolate each event to distinct layers of the ice, all of which corresponded to ice strata affected by volcanic ash (note the dark streak in the ice core image above). Whenever a volcanic eruption spread ash on the ice, it created a weaker layer. Even after hundreds more meters of ice have formed atop these weaker layers, the ice still breaks first in those layers, which may account for the ice stream’s higher-than-predicted flow. (Image credit: L. Warzecha/LWimages; research credit: A. Fichtner et al.; via Eos)

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    “Lively”

    In “Lively,” filmmaker Christopher Dormoy zooms in on ice. He shows ice forming and melting, capturing bubbles and their trails, as well as the subtle flows that go on in and around the ice. By introducing blue dye, he highlights some of the internal flows we would otherwise miss. (Video and image credit: C. Dormoy)

  • Bubbling Up

    Bubbling Up

    By volume, Lake Baikal is the world’s largest lake, holding over 20% of the planet’s fresh water. It’s also a major carbon sink, holding large amounts of methane. That’s the gas trapped in the frozen bubbles seen here. Baikal’s ice is exceptionally clear, making long trails of frozen bubbles visible during the winter. (Image credit: K. Makeeva; via APOD)

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  • Tracking Meltwater Through Flex

    Tracking Meltwater Through Flex

    Greenland’s ice sheet holds enough water to raise global sea levels by several meters. Each year meltwater from the sheet percolates through the ice, filling hidden pools and crevasses on its way to draining into the sea. Monitoring this journey directly is virtually impossible; too much goes on deep below the surface and the ice sheet is a precarious place for scientists to operate. So, instead, they’re monitoring the bedrock nearby.

    Researchers used a network of Global Navigation Satellite System (GNSS) stations like the one above to track how the ground shifted and flexed as meltwater collected and moved. They found that the bedrock moved as much as 5 millimeters during the height of the summer melt. How quickly the ground relaxed back to its normal state depended on where the water went and how quickly it moved. Their results indicate that the water’s journey is not a short one: meltwater spends months collecting in subterranean pools on its way to the ocean — something that current climate models don’t account for. Overall, the team’s results indicate that there’s much more hidden meltwater than models predict and it spends a few months under the ice on its way to the sea. (Image credit: T. Nylen; research credit: J. Ran et al.; via Eos)

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  • Trapped in Ice

    Trapped in Ice

    On lake bottoms, decaying matter produces methane and other gases that get caught as bubbles when the water freezes. In liquid form, water is excellent at dissolving gases, but they come out of solution when the molecules freeze. In the arctic, these bubbles form wild, layered patterns like these captured by photographer Jan Erik Waider in a lake on the edge of Iceland’s Skaftafellsjökull glacier. Unlike the bubbles that form in our fridges’ icemakers, these bubbles are large enough that they take on complicated shapes. I especially love the ones that leave a visible trail of where the bubble shifted during the freezing process. (Image credit: J. Waider; via Colossal)

  • Slushy Snow Affects Antarctic Ice Melt

    Slushy Snow Affects Antarctic Ice Melt

    More than a tenth of Antarctica’s ice projects out over the sea; this ice shelf preserves glacial ice that would otherwise fall into the Southern Ocean and raise global sea levels. But austral summers eat away at the ice, leaving meltwater collected in ponds (visible above in bright blue) and in harder-to-spot slush. Researchers taught a machine-learning algorithm to identify slush and ponds in satellite images, then used the algorithm to analyze nine years’ worth of imagery.

    The group found that slush makes up about 57% of the overall meltwater. It is also darker than pure snow, absorbing more sunlight and leading to more melting. Many climate models currently neglect slush, and the authors warn that, without it, models will underestimate how much the ice is melting and predict that the ice is more stable than it truly is. (Image credit: Copernicus Sentinel/R. Dell; research credit: R. Dell et al.; via Physics Today)

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    “Serenity”

    Peering from directly above, landscapes take on a whole different aspect. That idea is the heart of Vadim Sherbakov’s “Serenity,” filmed by drone. From seething waters and meandering rivers to eroded landscapes and twisting ice, there’s lots of fluid dynamics on display here. (Video and image credit: V. Sherbakov)

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