"Pop" Study May Impact Understanding of Aerosols

The bursting of bubbles is caused by the dissipation of a larger bubble into smaller ones—a finding with larger implications for current understanding of aerosols, according to a recent study at the School of Engineering and Applied Sciences.

SEAS graduate student James C. Bird, who led the study, found that the forces acting on a bubble cause the film to fold into itself and form a donut-shaped pocket of air. Then, the surface tension breaks the "torus of air" into a ring of smaller bubbles, Bird wrote in a press release.

The study's findings may modify existing conceptions of bubble-mediated aerosols that could have far-reaching consequences on health and climate research.

Prior to the recent study, scientists did not believe that bubbles larger than several millimeters produce tiny air-bound droplets when popped. Prevailing assumptions about the lack of aerosols created by larger bubbles downplayed the level to which bubbles might carry infectious diseases from sources of illness or contribute to the saline level in the air from ocean water.

The research team, which used high-speed cameras to document the rapid rupturing process, determined that its conclusions on the cascading effects of a popped bubble remain constant over different materials. Even bubbles from viscous liquids, such as oil, followed the same two-step procedure of rupturing.

The study's results will be published in Thursday's issue of Nature magazine.

—Staff writer Gautam S. Kumar can be reached at gkumar@college.harvard.edu.