Fresh winter snow blankets Chicago in this satellite image. Over on Lake Michigan, ice dots the coastline out to about 20 kilometers from shore. Darker regions near land mark thinner ice being pushed outward by the wind. Further out, the ice appears white and may be thicker thanks to wind-driven ice piling up. (Image credit: M. Garrison; via NASA Earth Observatory)
Tag: wind
Derecho-Induced Skyscraper Damage
Derechos are short-lived, intense wind storms sometimes associated with thunderstorms. Last spring, such a storm passed through Houston, leaving downtown skyscrapers with more damage than a hurricane with comparable wind speeds. Now researchers believe they know why a derecho’s 40 meter per second winds can badly damage buildings built to withstand 67 meter per second hurricane winds.
In surveying the damage to Houston’s skyscrapers, the team noted that broken windows were concentrated in areas that faced other tall buildings. In a wind facility, the team explored how skyscrapers interfered with each other, based on their separation difference. They looked both at conditions that mimicked a hurricane’s winds as well as the downbursts — strong downward wind bursts — that are found in derechos.
The researchers found that downbursts in between nearby buildings caused extremely strong suction forces along a building’s face — even compared to the forces seen with higher hurricane-force winds. Currently, these buildings are designed for hurricane-like conditions, but the team suggests that — at least in some regions — designers will need to take into account how downburst wind patterns affect a skyscraper, too. (Image credit: National Weather Service; research credit: O. Metwally et al.; via Ars Technica)
Fediverse Reactions
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Wind Sculptures
Vibrantly colored fabrics move in the breeze in artist Thomas Jackson’s outdoor installations. During the golden hours, he captures that movement in photographs like these. Jackson uses tulle, silk, and other everyday objects in his projects, and when finished, he takes a “leave no trace” approach, removing all materials and recycling them into new projects. Find more work on his website and Instagram. (Image credit: T. Jackson; via Colossal)
Seeking Rogue Wave Origins
Rogue waves — rare waves much larger than any surrounding waves — have long been a part of sailors’ tales, but their existence has only been confirmed relatively recently. The exact mechanisms behind them are still a matter of debate. Laboratory experiments with mechanically-produced waves have created miniature rogue waves, but we still lack real-world observations of their formation.
To that end, researchers sailed the Southern Ocean, known for its rough waves, during austral winter and observed the state of the wind and waves nearby using stereo cameras. They found that young wind-driven waves tend to be steeper, and they move slower than the wind, as they’re still drawing energy from it. Older waves, in contrast, were shorter, less steep, and less likely have white caps from breaking. Overall, they found that strong winds could more easily drive young waves into the nonlinear growth that leads to rogue waves. (Image credit: S. Baisch; research credit: A. Toffoli et al.; via APS Physics)
“Animaris Rex”
Eighteen meters long and powered only by the wind, artist Theo Jansen’s latest Strandbeest strolls the sand in this short video. Its complex movements — a swinging gait in some places and a caterpillar-like wave in others — are mesmerizing and life-like enough to almost make you wonder if the contraption truly is alive. See some of Jansen’s previous creations here. (Video and image credit: T. Jansen et al.; via Colossal)
Scooting Droplets
As a child, I always loved watching rain on the windows as I rode in the car. Hemispherical droplets got stretched by the wind flowing over them. But they never stretched smoothly; instead they seemed to shiver and shake unevenly. A recent study looks at a similar situation: drops of glycerin forced to slide along a horizontal surface under the force of the wind. Like the drops on my parents’ car, the glycerin gets stretched out into an elongated oval. Surface waves develop atop the drop and move downstream. The drops, the authors observe, move a bit like a crawling caterpillar, pilling up and smoothing out as they move. (Image credit: rain – A. Alves, experiment – A. Chahine et al.; research credit: A. Chahine et al.; via APS Physics)
This series of images shows an elongated droplet subjected to airflow moving from left to right. Waves form on the drop and move downstream in a fashion similar to a caterpillar crawling. Martian Flyover
Fly over a Martian crater in this incredibly detailed 8K video built from Mars Reconnaissance Orbiter imagery. Like Earth’s deserts, Mars is largely shaped by wind, and we get some fantastic views of sand ripples in this flyover. For reference, the vertical scale covered in the video image is roughly 1 kilometer. It’s pretty astounding to see this kind of detail from a spacecraft 250 kilometers away! (Video and image credit: S. Doran/NASA; via Colossal)
Raindrops on the Windshield
When I was a child, I was fascinated by the raindrops that shimmied along the windshield of our car. Some would slide up the glass. Some would run down. And some just seemed to wiggle in place, until the car’s speed changed. As common as this sight is, the physics of these droplets is quite complicated and not completely understood.
Each droplet has a host of forces on it: gravity flattening it or pulling it down an incline; a drag force from the wind flowing over it; and friction between the drop and the surface trying to pin it in place. Recently, scientists have developed a new mathematical model that captures some of the behaviors behind these drops. The work describes the wind speed necessary to move a drop of a given size sitting on a flat surface. The authors also explored how that critical wind speed changes when a drop sits on a tilted surface aligned or against the wind. (Image credit: P. Gupta; research credit: A. Hooshanginejad and S. Lee; via Science News; submitted by Kam-Yung Soh)
Strandbeest Evolution
Each spring, artist Theo Jansen releases his latest batch of wind-driven kinetic sculptures — known as Strandbeests — on a Dutch beach. This video compilation shows some of the newest strandbeests, including a variety of flying strandbeest. I find their motion mesmerizing. Some stroll, some undulate, some galumph their way across the the sands. Given their size — much larger than a person and often weighing 180 kilograms — it’s amazing to see them driven entirely by the wind through their sails. (Video and image credit: T. Jansen; via Colossal)
Explaining the Roaming Rocks
For nearly a century, the long meandering tracks etched into Death Valley’s Racetrack Playa remained a mystery. Clearly, some force was pushing the heavy rocks there and leaving behind these grooves. But with the remoteness of the location, it took investigators years to catch the rocks in action and solve the puzzle. For those who haven’t watched the video yet, I’ll refrain from revealing the answer here (though you can find it in previous FYFD entries)! I’ll just say that it requires all the right conditions to come together. (Image and video credit: Physics Girl; for related research see here)
