Published online 9 April 2008 | Nature | doi:10.1038/news.2008.746

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Bubbles spawn tiny twisters

Spinning vortices mirror giant hurricanes.

mini hurricanesThe tiny cyclones look eerily like a real storm.F. Seychelles & H. Kellay

After years of careful experimentation, physicists have finally created a tempest in a teapot-sized vessel. By heating a container topped with a soap bubble, a team of researchers has made centimetre-scale hurricanes that have similarities to their full-sized counterparts.

The experiment is simplicity itself, according to Hamid Kellay a physicist at the University of Bordeaux in France, who led the effort. First, you fill a beaker with a soapy solution. Then, "you take a straw and you make your bubble," he says.

The hemispherical bubble rests on top of the solution, which is heated to around 45 °C. As the solution warms, thermal plumes begin to form on the bubble's sides, and sometimes a large, single vortex, several centimetres in diameter, will form at the top (see video). "We thought they looked exactly like cyclones," says Kellay.

Round and round

To check the similarity, they recorded the motion of their little twisters with a digital camera and compared it with real-world data from the 2003–2004 hurricane season. The team found that the little and big hurricanes seemed to have similar random, thermal motion, even though their tracks were otherwise different.

Kellay is quick to point out that the analogy is probably fairly limited. Real-world hurricanes are created by different atmospheric processes, and their motion is heavily affected by Earth's rotation, whereas that of his bubbles is not. Nevertheless, he says, the bubbles might provide a little laboratory for understanding how large hurricanes interact with the turbulent air around them.

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"It's an interesting phenomenon," agrees Xiao-Lun Wu, a physicist at the University of Pittsburgh in Pennsylvania who also studies turbulence in soap films. The two-dimensional systems provide a well-controlled laboratory setting for physicists to study turbulence more generally, he says.

The team's work will appear in the 11 April issue of the journal Physical Review Letters1. 

  • References

    1. Seychelles, F., Amarouchene, Y., Bessafi, M. & Kellay, H. Phys. Rev. Lett. 100, 144501 (2008). | Article |
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