FYFD

Search results for: “waves”

  • Snoozing Sperm Whales Blow Bubbles

    Snoozing Sperm Whales Blow Bubbles

    Sperm whales like to nap under the water and away from the waves. They seem to do this in a vertical, head-up orientation. That makes sense, given that their enormous heads, which take up a third of their bodies, are full of oil, wax, and air–all buoyant materials. What’s less obvious is how the whales maintain their depth while sleeping. Why don’t they just bob right up to the surface with all that buoyancy?

    In a recent study, scientists attached devices to the whales that recorded their orientation, depth, and the sound of any bubbles the whale released. The team found that, over the course of a typical nap, whales let out 11 or so bubble bursts. This behavior appears to help them regulate their buoyancy so that they can maintain depth while they snooze. (Image credit: S. Granzotto; research credit: N. Freymond et al.; via Ars Technica)

    Fediverse Reactions
  • Featured Video Play Icon

    How Strings Vibrate

    Many of us have a mental image of strings vibrating like a swinging jump rope, but that’s not quite what you actually see. Instead, plucked strings often look strangely triangular, as Henry explains in this Minute Physics video. This more complicated shape comes from the way the string’s tension responds to the applied force of plucking, striking, or bowing.

    That doesn’t mean that the jump rope picture is entirely wrong, though. The triangular waves seen in the video are the shape you get when all the sine waves of the jump rope model get added together! (Superposition is fun.) (Video and image credit: Minute Physics)

    The triangular wave of a string plucked near one end.
    Fediverse Reactions
  • Stripping Mars’ Atmosphere

    Stripping Mars’ Atmosphere

    Mars was once a warmer, wetter place, swathed in a thick and protective atmosphere. Unlike Earth, Mars lacks a strong global magnetic field, which allows the solar wind to strip its atmosphere, but the exact mechanisms of that process have been unclear. But a new study has caught the process in action.

    Illustration of the Kelvin-Helmholtz instability occurring as the solar wind and Mars' electric field interact.
    Illustration of the Kelvin-Helmholtz instability occurring as the solar wind and Mars’ electric field interact.

    By combining simultaneous measurements from two spacecraft–NASA’s MAVEN and China’s Tianwen-1–the team was able to monitor the upstream solar wind conditions and the atmospheric ions escaping. They found that previously-observed “plasma clouds” in the Martian atmosphere result from a Kelvin-Helmholtz instability between the solar wind and Mars’ electric field. Within these clouds, the ion flux is ten to a hundred times greater than at steady-state conditions.

    This mechanism directly couples ion escape from Mars’ atmosphere to the solar wind, and it’s likely that this process plays out for other unmagnetized planets as well. (Image credit: Mars – NASA, illustration – C. Zhang et al.; research credit: C. Zhang et al.; via Gizmodo)

    Fediverse Reactions
  • Featured Video Play Icon

    Levitating By Squeeze Film

    We’ve seen a few different kinds of levitation here over the years, including via acoustic waves, aerodynamics, and Leidenfrost effect. Here, Steve Mould describes something a bit different: a levitation squeeze film driven by ultrasonic transducers. Like a vibrating droplet, the thing keeping surfaces apart here is a thin, lubricating layer of air. The vibration of the ultrasonic transducer squeezes and replenishes the air layer quickly enough that it can keep transducers aloft. Steve even manages to create a miniature airless “air hockey” table with it! (Video and image credit: S. Mould)

  • Salt and Dunes

    Salt and Dunes

    Photographer Barbara Brown captured these striking aerial views in Namibia. Coastal dunes and saltworks feature in the photos from Walvis Bay, where wind, waves, evaporation, and humankind have shaped the landscape. The colorful and dendritic dune images come from Sossusvlei, where the ephemeral Tsauchab River ends in the Namib Desert. Recent flooding left its mark on the dry landscape. (Image credit: B. Brown/IAPOTY; via Colossal)

    Fediverse Reactions
  • Convection Inside the Mantle

    Convection Inside the Mantle

    Most of what we know about Earth’s interior comes from observing how seismic waves–mostly from earthquakes–bounce around. As our observations have gotten better–more seisometers, better imaging techniques–scientists have identified two large anomalies sitting near the bottom of the mantle. Known as large low-velocity provinces, or LLVPs, these zones take up continent-sized areas beneath parts of Africa and the Pacific.

    Seismic waves show lower speeds in large, continent-sized zones that sit beneath Africa and the Pacific. These large low-velocity provinces (LLVPs) are outlined in red.
    Seismic waves show lower speeds in large, continent-sized zones that sit beneath Africa and the Pacific. These large low-velocity provinces (LLVPs) are outlined in red.

    The LLVPs are hot, which would normally make them buoyant, but their stationary nature suggests they are made up of extremely dense material. Narrow plumes of hot material make their way up from the LLVPs to form volcanic hotspots like those that made the Hawaiian and Galapagos Islands. Balancing that upward convection is the downward convection of former tectonic material carried into the mantle at subduction zones.

    What the LLVPs are made of remains an active research question. One suggestion is that they contain remnants of Theia, the planet thought to have impacted the proto-Earth to form our Moon. (Image credits: E. Garnero and C. Richardson; see also Physics Today)

    Illustration showing convection in the Earth's inner mantle. Former tectonic material subducts downward in dark blue zones. The large low-velocity provinces (LLVPs) are shown in orange. Hot-spot volcanic activity is seen at the surface (black triangles) above narrow plumes that lift material from the LLVPs toward the surface.
    Illustration showing convection in the Earth’s inner mantle. Former tectonic material subducts downward in dark blue zones. The large low-velocity provinces (LLVPs) are shown in orange. Hot-spot volcanic activity is seen at the surface (black triangles) above narrow plumes that lift material from the LLVPs toward the surface.
    Fediverse Reactions
  • Pacific Surf

    Pacific Surf

    Life in Venice Beach lends itself to wave-watching, or so it seems for photographer Craig Hubbard. His portraits of waves and surfers are ethereal, every swell capped by a cloud-like swath of spray. Somehow, every photographer seems to capture breaking waves a little differently! (Image credit: C. Hubbard; via Colossal)

    Fediverse Reactions
  • Swirls Above the Southern Ocean

    Swirls Above the Southern Ocean

    In the Southern Ocean, obstacles are sparse. But the ice-cloaked volcano of Peter I Island is tall enough at over 1600 meters to disrupt the wind. At steady wind speeds between about 18 to 54 kilometers per hour, flowing past the island creates vortices that shed from one side and then the other. The result is a von Karman vortex street like the one seen here, flowing toward the upper right.

    The overlaid ripple structures in the cloud layer are reminiscent of gravity waves. Perhaps, the wind’s passage made some lee waves that the vortices distorted? (Image credit: M. Garrison; via NASA Earth Observatory)

    A von Karman vortex street stretches downstream from Peter I Island.
  • Infrasound Fire Suppression Goes Commercial

    Infrasound Fire Suppression Goes Commercial

    Sprinklers have long been the go-to fire protection for commercial properties and some residences. Dousing a fire in water not only puts out the flames but cools the surroundings and helps prevent reignition. But it requires complicated infrastructure and can damage buildings and their contents. Back in 2015, students were experimenting with an alternative fire extinguisher that used sound below the range of human hearing; now a company is pitching a version of that technology for replacing sprinklers.

    As described by Ars Technica, this infrasound system can detect and put out a small kitchen fire in under a minute. But fire fighting experts warn that there’s a big difference between a fire small enough for a fire extinguisher to handle and the kinds of fires sprinklers put out. With lives at stake, the burden of proof is significant for Sonic Fire Tech and any other company that wants to get their infrasound “sprinkler” system cleared for use in buildings. (Image credit: I. Azevedo; via Ars Technica)

    Fediverse Reactions
  • “Sunny Seaweed Surf”

    “Sunny Seaweed Surf”

    Seaweed sways in the surf in this photograph by Billy Arthur. I always love how waves look like a stormy sky when viewed from below. This image is extra neat because of the contrast with the sunbeams shining through the still surface on the right side of the image. Sun and storm on the verge of colliding. (Image credit: B. Arthur/BWPA; via Colossal)

    "Sunny Seaweed Surf" by Billy Arthur

More posts