Surface tension is the result of an imbalance between intermolecular forces near an interface. Imagine a water molecule far from the surface; it is surrounded on all sides by other Keep reading
Month: April 2025
Flag Flapping
Everyone has watched a flag flutter in the breeze, but you may not have given much thought to it. One of the earliest scientists to consider the problem was Lord Keep reading
Porous Fingers
If you inject a less viscous fluid, like air, into a narrow gap between two glass plates filled with a more viscous fluid, you’ll get a finger-like instability known as Keep reading
The Rose-Window Instability
This polygonal pattern is known as the rose-window instability. It’s formed between two electrodes – one a needle-like point, the other flat – separated by a layer of oil. The Keep reading
Detergency
Have you ever wondered just how detergents are able to get grease and oil off a surface? This simple example demonstrates one method. In the top image, a drop of Keep reading
Sunglinting Seas
Sunlight reflecting off the Earth can reveal a remarkably rich picture of our planet’s activity. The silver-gray areas seen in this satellite image are sunglint, where lots of light is Keep reading
Surfing Mists
Watch your hot cup of coffee or tea carefully, and you may notice a white mist of tiny micron-sized droplets hovering near the surface. These microdroplets are a little understood Keep reading
Pelican Diving
Pelicans, like many sea birds, are aerial divers. They spot their prey from high above, bank, and dive into the water to catch the fish. Although they hit the water Keep reading
Controlling Leidenfrost Drops
On a surface much hotter than their boiling point, droplets can surf on a layer of their own vapor due to the Leidenfrost effect. Recent research has shown that textured Keep reading
Convection
Blue paint in alcohol forms an array of polygonal convection cells. We’re accustomed to associating convection with temperature differences; patterns like the one above are seen in hot cooking oil, Keep reading