Lines of waves emerge from thick morning fog in this series by photographer Raf Maes. The eerie, slightly surreal images were captured in Venice, near Los Angeles. So often ocean photography features huge, turbulent breaking waves. I find it really neat to see these long, unbroken wave crests appearing from the mist. (Image credits: R. Maes; via Colossal)
That the wind causes ocean waves is obvious to anyone who has spent time near the water, but the details of that process remain fuzzy. Many of the explanations — like the Kelvin-Helmholtz instability — only explain part of the process, usually the beginning when the waves are very small. As the waves get larger, they affect the wind in turn, complicating matters.
As messy as the theory gets, our ability to measure the wind and water in situ is limited, too. Just look at this wild research platform oceanographers designed to study wind and waves. It’s part of a 355-ft vessel that’s towed out to sea horizontally and then flipped so that 300 feet of it remain underwater to stabilize the remainder for measurements. Even with equipment like this, measuring the turbulent air and water near the ocean-sky interface is incredibly difficult.
This review article gives a nice overview of different historical efforts to explain how wind makes waves and provides a snapshot of the latest research in the area. (Image credit: R. Bilcliff; see also N. Pizzo et al.)
Coastal marshes are a critical natural defense against flooding. The flexible plants of the marsh both slow the water’s current and help damp waves. As a result of that hydrodynamic dissipation, marshes help protect against erosion and reduce the magnitude of flooding events. But coastal managers looking to maintain or improve their marshes in order to mitigate climate-change-driven storms need to be able to predict what level of vegetation they need.
To that end, a team of researchers has built a new model to better capture the flow effects of marsh grasses. Building from an individual, flexible plant (as opposed to a rigid cylinder, as grass is often represented), the authors constructed a model able to predict wave dissipation for many marsh configurations, which should help better predict the infrastructure changes needed in different coastal regions. (Image credit: T. Marquis; research credit: X. Zhang and H. Nepf; via APS Physics)
As sea ice disappears in the Arctic Ocean, it leaves behind higher waves on the open water. These large waves help inject sea salt and organic matter into the atmosphere, where they can serve as nucleation sites for ice crystals. A recent field expedition in the Chukchi Sea observed high concentrations of organic particulates in the air and more ice-producing clouds during periods of high wave action. So, oddly enough, the loss of sea ice may lead to more cloud cover and precipitation in the Arctic (though the effect is likely not strong enough to entirely mitigate the effects of ice loss). It’s another example of the intricate and complex connections between ice, ocean, and atmosphere in the Arctic climate. (Image credit: A. Antas-Bergkvist; research credit: J. Inoue et al.; via Gizmodo)
Meteotsunamis, or meteorological tsunamis, are large waves driven by weather rather than seismic energy. Although they occur along shorelines throughout the world, forecasters have very little infrastructure in place to predict or detect them. But a new study of an April 2018 meteotsunami on Lake Michigan (pictured above) has provided evidence that existing models may be able to forecast these events.
The Lake Michigan meteotsunami was driven by an atmospheric gravity wave, which carried with it a substantial pressure drop. Most of the time such waves travel faster or slower than water waves, and there is little to no interaction. But on this day, the atmospheric wave and the water waves were traveling at the same speed in the same direction, creating a resonance that strengthened the water wave.
Using existing National Oceanic and Atmospheric Administration (NOAA) models, researchers were able to reconstruct the event digitally, with results that agreed well with observations. That success means that forecasters may be able to predict the events ahead of time, potentially saving lives. (Image credit: D. Maglothin; research credit: E. Anderson and G. Mann; via Gizmodo)
Whether you’re watching ducks cruise by on a pond or a boat making its way across the ocean, you’ve probably noticed a distinctive V-shaped wake. This shape is known as a Kelvin wake, and it forms because waves in water don’t all move at the same speed. Instead, the speed a wave travels at depends on its wavelength; smaller wavelengths travel slower than larger ones, a phenomenon known as dispersion. The characteristic shape of a Kelvin wake is the result of many waves of different wavelength (and therefore speed) added together. (Video and image credit: Minute Physics)
Filmmaker Chris Bryan captures surfer Kipp Caddy as he rides an enormous wave in “Dancing With Danger.” Nothing quite captures the majesty of these powerful flows like high-speed videography. Enjoy the break, the spray, and those awesome rib vortices. (Image and video credit: C. Bryan)
The same dynamic forces that make coastlines fascinating create perennial headaches for engineers trying to maintain coastlines against erosion. This Practical Engineering video discusses some of the challenges of coastal erosion and how engineers counter them.
In a completely undeveloped coastline, waves and storms erode the shoreline while rivers and currents replenish sand through sedimentation. Manmade structures tend to strengthen erosion processes while disrupting the sedimentation that would normally counter it. Beach nourishment — where sand gets dredged up and deposited on a beach — is an engineered attempt to replace natural sedimentation.
Dunes, mangrove forests, and wetlands are all nature’s way of protecting and maintaining coastlines. We engineers are still learning how to both utilize and protect shorelines. (Image and video credit: Practical Engineering)
The “Waves” installation by artist Daniel Palacios appears deceptively simple, just a rope mounted between two motors. But once the motors start spinning, it is anything but. The installation shifts in response to those around it, creating varying numbers of steady, standing waves or even wildly chaotic ones that whistle through the air. It’s a neat visualization of one of the most commonly-measured quantities in physics: the changes in a wave with time. (Video and image credit: D. Palacios; via Flow Vis)
The Seoul Aquarium is now home to an enormous crashing wave, courtesy of design company d’strict. Check out several different views of the anamorphic illusion in their video above. There’s no word on the techniques used to generate the animation, but it’s certainly a cool visual! (Image and video credit: d’strict; via Colossal)
