During lockdown, photographer Doris Mitsch turned her eyes to the sky and began capturing these mesmerizing composite images of animals in flight. Vultures, crows, starlings, gulls, and bats all feature in her series. Some images, like “Lockdown Vulture (Signature)”, feature a single bird’s movement over a minute. Others show entire flocks over extended periods.
I love how the images capture a sense of speed. Given equal timing between images, the lines with more space between each snapshot of a bird indicate a faster speed. It’s a bit like having particle image velociometry frames stacked atop one another! (Image credit: D. Mitsch; via Colossal)
In many geophysical and metallurgical processes, there is a stage with a porous layer of liquid-infused solid known as a mushy layer. Such layers form in sea ice, in cooling metals, and even in the depths of our mantle. Within the mushy layer, temperature, density, and concentration can vary dramatically from one location to another.
The image above shows a mushy layer made from a mixture of water and ammonium chloride. Above the mushy layer, green plumes drift upward, carrying lighter fluid. Look closely within the mushy layer and you’ll see narrow channels feeding up to the surface. These are known as chimneys. In sea ice, chimneys like these carry salty brine out of the ice and into the seawater, increasing its salinity. See this Physics Today article for more details on the dynamics of mushy layers. (Image credit: J. Kyselica; via Physics Today)
The splash of a droplet is a surprisingly complex phenomenon, depending not only on the droplet’s characteristics but also the surrounding air pressure, the roughness and temperature of the impact surface, and the surface’s curvature. In this study, researchers investigated the effects of surface curvature on splashing, finding that it’s harder for a drop to splash on spheres of smaller radius than ones with a larger radius of curvature.
In Image 1, the falling droplet coats the 2-mm sphere with no sign of splashing. But as the radius gets larger (Images 2 and 3), splashing becomes more and more pronounced. They found that the splash suppression is due to a modification of the lift force on the leading edge of the lamella, the thin liquid layer created as the drop impacts and spread. (Image, research, and submission credit: T. Sykes et al.; also available here)
In 1904, Scottish architect Charles Rennie Mackintosh created the Hill House, a masterpiece of modern design decades ahead of its time. Unfortunately, the Portland cement used for the house’s exterior has not held up well to a century of Scottish rains. As water saturated the cement, it began to dissolve and crumble. So to save the property, conservators commissioned the giant chainmail Box that currently surrounds the house. It protects the house from rain while allowing ventilation that dries the house out slowly. As an added bonus, the superstructure allows visitors to appreciate the house from new angles. (Video credit: T. Scott; via Colossal)
Ionic liquids are essentially salts in a liquid form. In these images, a mixture of water and ionic liquid separates when heated. This phase separation causes the initial mixture to break into two regions: one low in ionic liquid and one rich in ionic liquid. Because the surface tensions of these two phases are different from one another, complex flow patterns form. (Image and research credit: M. Pascual et al.)
I’m not normally one to talk about myself here on FYFD. This site was made to keep the focus on the science, but I’m making an exception today to share a very special exhibit that I’m a part of: the #IfThenSheCan Exhibit, which opens today at the Smithsonian in Washington, DC as part of their #WomensFuturesFestival.
The exhibit features over 120 statues of real women in STEM careers — everything from robotics to marine biology, artificial intelligence to aerospace engineering. It is an absolutely amazing bunch of women, and I am so honored to be a part of it.
My statue, while on display in Dallas. Photo by Regina Binz.
If you’re in the DC area before March 27th, be sure to swing by the National Mall and see the statues. (If not, you can take a virtual tour, too!) Currently, they are all located at the Arts + Industries Building, the Smithsonian Castle and the adjacent Enid A. Haupt Garden, but after March 7th, some of the statues will move to other museums around the Mall. Mine is heading to the National Air and Space Museum!
When I was twelve years old, I visited DC for the first time, and everything about that trip made a huge impression on me. I was in awe of the history, the memorials, the public transit, and, most of all, the National Air and Space Museum. My parents complained that every time we walked the Mall, I made a beeline — as if drawn by a magnetic field — right up the steps of that building. To be a part of that museum now, some twenty years later, is something I never could have imagined.
I’m so proud to be part of this initiative full of amazing women inspiring the next generation of STEM innovators! Special thanks to AAAS and Lyda Hill Philanthropies for making it all possible. (Image credits given in each description/caption.)
Soap films are ephemeral and ever-changing. The shifting concentration of surfactants along the surface of the film, combined with thermally-driven convection, keeps the fluid in motion. The shifting colors reflect subtle changes in the soap film’s thickness. Over time, gravity drains fluid from the top of the film, thinning it to the point that it appears black. This photo from Bruno Militelli captures all of that detail in a striking and fascinating image that earned him 2nd place in the Manmade category of the Close-Up Photographer of the Year awards. You can find more winners of the competition here, and more of Militelli’s work on his website and Instagram. (Image credit: B. Militelli)
A fixed cylinder will shed alternating vortices in its wake, but one allowed to oscillate forward and backward in the flow instead sheds simultaneous vortices. The shape of the wake still depends on the flow’s velocity. At low flow speeds, the two vortices are the same size when they shed. At higher velocities, the two vortices still shed simultaneously, but one will be large while the other is small. The larger vortex moves faster and travels downstream, but the smaller, slower vortex drifts inward. In the next shedding cycle, the small and large vortices switch positions, creating alternating symmetric shedding. (Image and video credit: P. Boersma et al.)
Water is an odd substance because it is densest at 4 degrees Celsius, well above its melting point at 0 degrees Celsius. This density anomaly means that melting ice takes on very different shapes, depending on the temperature of the water surrounding it. At low temperatures (under 4 degrees Celsius), the cold water melting off the ice is denser than the surroundings, so it sinks. The sinking fluid melts lower portions of the ice faster, leading to an inverted pinnacle (Image 1).
In contrast, at higher temperatures (above 7 degrees Celsius), the meltwater is lighter than the surroundings and therefore rises, creating an upward-pointing pinnacle (Image 3). At intermediate temperatures, some areas of the ice see rising meltwater and some see sinking. This complicated flow pattern sets up vortices that result in a scalloped edge along the ice (Image 2). (Image and research credit: S. Weady et al.; via APS Physics)
Line-like clouds criss-cross the Pacific Ocean in this satellite image. Each one is a ship track, a remnant left behind a passing ship. As they travel, ships leave a trail of exhaust that seeds the atmosphere with aerosols that serve as additional nucleation sites for clouds. The tiny particles interact with existing low-level clouds, making them brighter. Of course, the aerosols are present in the wake of ships regardless of whether they seed clouds that we can observe. (Image credit: J. Stevens; via NASA Earth Observatory)
