Miniature version of Jupiter's atmosphere sheds light on its good looks

University of Oxford news release, 8 December 2004

Researchers in the Department of Atmospheric, Oceanic and Planetary Physics have recreated in miniature the formation of the attractive bands of Jupiter and Saturn's atmospheres.

Jupiter's colourful atmosphere has a characteristic banded pattern: 'zonal jets' flow in alternating directions, parallel to lines of latitude. Saturn's atmosphere has this structure too, and there are even faint zonal jets in the terrestrial ocean. Yet the origin of the banding is still not clear.

The favoured hypothesis is that what creates the banding is a latitudinal variation of the Coriolis force (the apparent deflection in the paths of air or water caused by the Earth's rotation), called the planetary beta effect. This has been hard to test in experiments aiming to mimic the planetary atmosphere, because to make the fluid sufficiently turbulent, the scale needs to be very large.

Now Professor Peter Read and his colleagues have achieved a simulation supporting the planetary beta effect theory. They used a turntable 14 metres in diameter, supporting a shallow layer of salty water in which convection was maintained (imitating that in the gas-giant atmospheres) by spraying denser, saltier water on top. The planetary beta effect was reproduced topographically by a conical slope in the bottom of the fluid tank. Small particles suspended in the flow reveal banded zoning. The team reported their findings in Geophysical Research Letters.

Professor Read said: 'The jets are not as neat as those on Jupiter, but they show that the basic idea works. We believe these results are quite significant for both planetary meteorology and oceanography. The fact that we were able to recreate was happening at a planetary level using simple convection on a laboratory scale suggests stronger similarities in the circulations of the oceans and the outer planet atmospheres than previously realised.'