In black and white, the towering power of a thunderstorm looks almost apocalyptic. Photographer Mike Olbinski’s latest storm timelapse, “Breathe,” features roiling turbulence, distant downpours, and eerie mammatus clouds. Supercell thunderstorms churn and rotate over empty horizons. Billowing cumulus clouds condense from bright skies. Flashes of lightning reveal the outlines of massive thunderheads. It’s a beautiful glimpse of atmospheric fluid dynamics in action, with every texture magnified and enhanced by the stark black and white palette. (Video and image credit: M. Olbinski; via Gizmodo)
Every year I look forward to the APS DFD conference in November. It brings thousands of researchers together to share the latest in fluid dynamics. So much goes on in those three days that it’s impossible to capture, but last year I teamed up with Tom Crawford and the Journal of Fluid Mechanics to attempt just that. We interviewed 50 researchers on their projects, and we’ll be bringing you their work, in their words, each month leading up to the 2018 APS DFD meeting.
This first video focuses on some of the awesome entries to the 2017 Gallery of Fluid Motion. Watch to learn about oil droplets that go flying everywhere when you’re cooking, balls that walk on water, the water music of Vanuatu and more! To see the videos we discuss and all the other entries, go to gfm.aps.org. (Video credit: N. Sharp and T. Crawford)
On occasion in the late fall and early winter, the Grand Canyon can fill with clouds of fog. This occurs when a layer of warm air traps cold, moist air inside the canyon, creating what’s known as a temperature inversion. The trapped air’s moisture condenses into fog, creating the appearance of a cloud sea lapping at the canyon walls. Such inversions often proceed a big snowstorm, as shown in this video. (Video and image credit: H. Mehmedinovic / SKYGLOWPROJECT; via Gizmodo)
Black holes, like the collapse of a cavity in a fluid, are a singularity – a point where the mathematical rules we use to describe physical systems break down. No one knows what exists in a black hole, but the short film “Intra” explores one theory – that the exit to a black hole is a white hole, a singularity from which time and space themselves are born. The journey from one to the other is illustrated in the film with CGI visualizations of a black hole (a la Interstellar) and with fluid dynamical sequences depicting diffusion and chemical reactions driving flows. Although no true white holes have ever been observed, there are fluid dynamical analogs for them, namely circular hydraulic jumps, like the one you can make in your kitchen sink! (Video credit: T. Vanz et al.)
Liquid sunbursts and swirling aquatic roses abound in photographer Mark Mawson’s work. Images like these are created from dropping ink into water and photographing it as it diffuses. For the roses, the tank is additionally stirred or spinning to create the vortex-like appearance. Check out his website for more striking images, including more billowing ink, some great splashes and beautiful turbulent mixing between coffee and milk. (Image credit: M. Mawson; submitted by clogwog)
When viewed at the right pace, clouds can flow. This timelapse of fog over Mt. Tamalpais State Park near San Francisco shows clouds moving over the hills there. Physically, this flow is an example of a familiar phenomenon known as a hydraulic jump. It happens when a fast-moving flow moves into a region of slower flow. The kinetic energy of the incoming flow gets transferred into potential energy, causing the flow to suddenly rise in height. It can also trigger turbulence, as seen on the right side of the animation. Watch carefully along a river, and you’ll see the same thing happening. Or, if your kitchen sink has a flat bottom, you can create a circular hydraulic jump just by turning on the faucet. You’ll get a region of fast flow right where the water impacts the basin, and a little ways out, you’ll see a circular jump where the water is suddenly taller and slower. That’s a hydraulic jump, too! (Image credit: Nicholas Steinberg Photography, source; submitted by Madi R.)
The characteristics of a surface can have a major impact on the form a flow takes. The photo above shows a corrugated, almost pinecone-like water surface. It’s the result of a sheet of water flowing over a surface with alternating bands of hydrophobic (water-repelling) and hydrophilic (water-loving) properties. The water sheet narrows over hydrophobic sections and expands over hydrophilic ones. Gravity, inertia, and surface tension compete to create the overall braided appearance. You can see a top-down view of the flow in the original poster. (Image credit: M. Grivel et al., source)
With patience and timing, one can create remarkable sculptures with fluids. To capture this shot, Moussi Ouissem used two droplets, perfectly timed. The first fell through the soap bubble (which stayed intact thanks to its powers of self-healing) and hit the pool of water. The impact caused a cavity, which then inverted into a Worthington jet. The second drop was timed to impact the column of the jet, creating the saddle-shaped splash seen here. Ripples in the bubble are still visible from the passage of the second drop, and several satellite droplets are signs of the violence of the impacts. (Image credit: M. Ouissem)
It’s a cliché to claim that the sky is bigger in the American West, but the wide, open views in that region do offer a very different perspective on weather. Photographer Mike Olbinski’s works give viewers a taste of that perspective of far-off thunderstorms, towering anvil clouds, and massive downpours in the distance. At the same time, many of his sequences illustrate the birth and death of these massive storms. As warm, moist air rises, a puffy cumulus cloud (below) swells upward as fresh moisture condenses. When it reaches a thermal cap and can rise no further, precipitation begins to fall, dragging surrounding air with it. This is the mature stage of a storm, when both updrafts and downdrafts exist simultaneously.
Eventually, the storm’s power begins to wane as the downdrafts cut off the updrafts that feed the storm. Sometimes this occurs in a massive downdraft where cool air sinks straight down and, upon encountering the ground, spreads radially outward. In dry regions, this outward burst of ground-level winds can pick up dirt, dust, and sand, forming a wall-like haboob (below) that advances past the remains of the storm. Watch the entire video to see some examples in their full glory! (Video and image credit: M. Olbinski, source; via Rex W.)
The meeting of land and sea often creates a rich and colorful environment. This satellite image shows Mexico’s Laguna de Términos, a coastal lagoon off the Gulf of Mexico. A skinny barrier island forms the lagoon’s two connections to the ocean; the eastern side is the usual inlet (right), while the western side forms an outlet. Rivers feed freshwater into the lagoon from the south and southwest. These introduce sediments that cause some of the lighter swirls in the image. Winds and tides also contribute to this turbidity. The sheltered nature of the lagoon allows fresh and salt water to mix gradually, providing harbor for many forms of life. Oyster beds thrive in the river mouths; seagrasses prefer the calmer, saltier waters, and mangrove trees line the shore, slowly desalinating water for themselves as their roots shelter young fish and shrimp. (Image credit: NASA Earth Observatory)
