Marangoni effect Tears of wine Surface tension Commentary

James Thomson, Carlo Marangoni thermodynamics

Marangoni effect

The Marangoni effect gives wine legs. The Marangoni effect stabilizes soap bubbles. The Marangoni effect does not cause the Cheerios effect but helps explains the lava lamp. The Marangoni effect stabilizes convection cells in pots of tomato soup. The Marangoni effect helps dry silicon wafers while processing integrated circuits. The Marangoni effect makes my leaky faucet drip and breaks a falling stream into a sequence of drops that a strobe light seems to freeze in place or maybe that’s just surface tension and gravity.

Tears of wine

James Thomson observed “tears of wine” and explained it as the effects of differences of surface tensions of water and alcohol. Streams of droplets described as curtains or legs appear not because of glycerin in the wine but from separation of water and alcohol, alcohol evaporating more readily and having a lower surface tension, causing the water to flow away from it.

Surface tension

Inside a bubble, a molecule of water bonds with neighbors balanced in all directions, but at a surface all its efforts pull inward and across the surface. Thus explains the magical ability of water striders to stride water, of beads of water to assume a spherical shape, and of soap bubbles to float in the air.