Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
The Shape of Rain
In our collective imagination, a raindrop is pendant shaped, wide at the bottom and pointed at the top. But, in fact, a falling raindrop experiences much more complicated shapes. Here, researchers blow a jet of air onto a still droplet, a good facsimile for a raindrop falling through the atmosphere. The jet of air first…
Jamming Soft Grains
Hard granular materials — sand, gravel, glass beads, and so on — can flow, but, in narrow regions or under large forces, they can also jam up, essentially turning into a solid. Soft particles can also flow and jam, but do so under different conditions than hard particles. One group of researchers used a custom-built…
Martian Auroras
Auroras happen when energetic particles — usually from the solar wind — interact with the atmosphere. Here on Earth, they’re most often found near the poles, where our strong global magnetic field converges, funneling particles down from space. Our neighbor Mars has no global magnetic field. Instead, its magnetic field is a hybrid of two…
“Ink In The Water. Mix One.”
In this ASMR video, black ink diffuses in water. When the video starts, the ink is so diffuse that it’s not apparent the video is playing backward. It’s only as specific structures — things like Rayleigh-Taylor instabilities, plumes, and jets — coalesce from the background that we recognize the time reversal. Though it’s probably unintentional,…
Water Suspected Beneath Mars
The surface features of Mars — crossed by river deltas and sedimentary deposits — indicate a watery past. Where that water went after the planet lost its atmosphere 3 – 4 billion years ago is an open question. But a new study suggests that quite a bit of that water moved underground rather than escaping…
Breaking Down a Water-Powered Timer
In his latest “cutaway” video, Steve Mould takes a look at how you can nest siphons to create a system that periodically flushes itself. This kind of water-powered timer is useful in, say, public restrooms with a urinal system that collectively flushes every once in a while. In the video, Mould talks through each step…
Shaped Splashes
When a raindrop hits a leaf, it spreads out into a rimmed sheet that breaks up into droplets. These tiny drops can carry dust, spores, and even pathogens as they fly off. But many leaves aren’t smooth-edged; instead they have serrations or teeth. How does that affect a splash? That’s the question at the heart…
A Triangular Prominence
Our Sun is a maelstrom of light and heat, a constant battlefield for plasma and magnetic fields. This recent prominence, captured by Andrea Vanoni and others, bore a striking triangular shape. This fiery outburst — larger than our entire planet — formed and broke up over the course of a single day. The wavy solar…
“Starlit”
In “Starlit,” filmmaker Roman de Giuli leverages paint, ink, water, and oil to create astronomical views. Colorful droplets spin past like neon exoplanets. Shards of glitter form comets. Satellite droplets become moons about their larger sibling. (Video and image credit: R. de Giuli)
Catching Krill With Bubble Nets
On their own and in groups, some humpback whales enclose their prey in bubbly columns before feeding. The whales build these bubble nets intentionally, swimming in a ring at a constant speed while producing bursts of air from their blowhole. After observing hundreds of bubble nets created by dozens of whales, researchers concluded that whales…