Celebrating the physics of all that flows with Nicole Sharp, Ph.D.
- Profile
Roll Clouds
The roll cloud, or Morning Glory cloud, is a rare phenomenon that looks rather like a horizontal tornado. In reality, it is part of a soliton wave traveling through the atmosphere. At its leading edge, moist air is forced upward, causing water vapor to condense, and, at the trailing edge, air moves downward, dissipating the…
Boiling on Mars
Today’s Mars is cold and dry, with a thin and insubstantial atmosphere. One of the challenges facing planetary scientists is unraveling the processes behind the complex terrain we can observe on the surface. Without flowing water, how do we explain these features? A new experiment suggests that the answer lies in boiling. Surface conditions on…
Silent Flying
As nocturnal hunters, owls are aerodynamically optimized for stealthy flying. This clip from BBC Earth demonstrates just how quiet a barn owl is in flight compared to a pigeon or a peregrine falcon. The owl’s large wingspan relative to its body size gives it enough lift that it does not have to flap often, allowing…
The Bubble Nebula
This spectacular Hubble image shows the Bubble Nebula. The source of this nebula is the star seen toward the upper left side of the bubble. This massive, super-hot star has ceased to fuse hydrogen and is now fusing helium, powering its way to a likely end as a supernova. As it burns, the star emits…
Striking Oobleck
Mixing cornstarch and water creates a fluid called oobleck that has some pretty bizarre properties. Oobleck is a shear-thickening, non-Newtonian fluid, which means its viscosity increases when you try to deform it with a shearing, or sliding, force. But as the Backyard Scientist demonstrates above, striking oobleck with a solid object produces some spectacular and…
Emulsion Impact
Emulsions – mixtures of two immiscible fluids – are quite common; the oil and vinegar combination used in many salad dressings is one. The image sequence above shows the first 800 microseconds of the impact of a similarly emulsified droplet. The outer drop, seen on the left, consists of a water/glycerin mixture, and inside the…
Mediterranean Currents
Ocean currents play a major role in the weather and climate of our planet. This video shows a simulation of the surface ocean currents in the Mediterranean and Atlantic over an 11-month period. Each second corresponds to 2.75 days. You’ll see many swirling eddies in the Mediterranean and more flow along the coastlines in the…
Bubbles and Films Merging
As we’ve seen before, a water droplet can merge gradually with a pool through a coalescence cascade. It turns out that the coalescence of a soap bubble with a soap film can follow a similar process! Initially, the bubble and film are separated by a thin layer of air. Once that air drains away and…
A New Cloud
These unusual and spectacular clouds are known as undulatus asperatus. Though they have been proposed as a new type of cloud, they are as yet officially unrecognized. Despite their dramatic appearance, these clouds are not associated with storms. Instead, they’re thought to form in a process similar to mammatus clouds, where wind shear at the…
Coastal Upwelling
Cool temperatures and abundant nutrients make the waters off the western coast of North America especially biologically productive. This image is a composite of satellite data highlighting large phytoplankton blooms in the California Current. This current runs southward along the coastline, and, like other eastern boundary currents, it experiences strong upwelling, or rising of colder,…