Soap bubbles predict circling winds

Meteorologists have been using an unusual tool to predict the wind intensity and strength of hurricanes and typhoons – soap bubbles. Researchers from the Laboratoire Ondes et Matière d’Aquitaine used soap bubbles to model atmospheric flow. They carried out simulations of flow, reproducing the curvature of the atmosphere and approximating as close as possible a simple model of atmospheric flow. “We used soap bubbles because they consist of a thin membrane or film that is fluid, i.e. membrane patches or film patches can move around the bubble,” researcher Hamid Kellay told Laboratory News. “The thickness of this membrane is only a few micrometres and the flow on this film is therefore nearly two dimensional (confined only to the film). This parallels the atmosphere, a shell of about 10km in thickness and that spans a large area.” “We used half bubbles that we deposited by blowing on a hot surface wetted with soap water beforehand,” he continued. “Once blown, the bubble surface shows a lot of activity due to the heating from underneath. This gives rise to thermal convection on the surface of the bubble. Out of this agitation, vortices appear once in a while. It is these vortices which (visually) look like cyclones, and it is their rotation speed which we measured and tracked in time.” Researchers were able to obtain vortices resembling tropical cyclones and whose rotation rate and intensity exhibit astonishing dynamics – weak after birth and increasing significantly over time. Following this period of growth, the vortex attains its maximum intensity before entering a period of decline. By analysing the rate of rotation of the vortices, researchers were able to find a simple relationship that accurately describes the evolution of intensity. This can then be used to predict the maximum intensity of the vortex and how long it will take to reach it. The team applied their findings to around 150 tropical cyclones occurring in the Pacific and Atlantic oceans, showing that the relationship held true for such low-pressure systems. Their results were published in Nature Scientific Reports. Intensity of vortices: from soap bubbles to hurricanes