The spirals and curls of Jupiter and Saturn may look fascinating, but they are turbulent storms that are out of this world literally and otherwise. Nothing like this happens on Earth.
Stormy storms on these gas giants are believed to arise from the lower atmosphere, just like those on our planet – until now. New research suggests that these terrestrial storms are likely to be driven by deeper internal forces rather than the external forces that burn storms just above the earth’s surface. Simulations of Jupiter and Saturn have shown that their weather systems, from cyclones and anticyclones to rays and magnetic clouds, are mostly due to violent internal processes.
“By modeling the dominant dynamic features found on the surface of Jupiter and Saturn, namely zone rays and storms / vortices, we can learn about what drives them and their connection to the planetary deep interior,” said Rakesh Kumar Yadav , who led a study recently published in Scientific progress.
There are more storms breaking on Jupiter and Saturn than just the big red spot and Saturn’s hexagonal storm that has received the most attention. One of the last things Cassini radiated back before disappearing into Saturn’s atmosphere forever was gravity data, and it helped Yadav’s team, along with data from the Juno mission, determine that jet streams on both planets should shed thousands of miles deep. This led to questions asking whether some of the storm vortices that can be seen on these planets spawn from convection that occurs far below the surface.
To find out how storms could possibly be born in the intestines of these planets, the research team modeled what they called a “thin shell” and “thick shell” simulations. Both of these approaches went beyond simply assuming where weather systems appear. Each type of simulation included in the rapid convection causing turbulence in planet-shaped spherical shells that were programmed to rotate like the planets they simulated.
On these gas giants, convection, as it is on Earth, is caused by warmer, less dense gas rising and colder, denser gas sinking. Although only gas is involved here, it can technically happen to any liquid or substance that can flow and change shape when a force acts on it to change.
The thin shell case examined what goes on in convection layers in the upper atmosphere of Jupiter and Saturn. Turbulence occurs between darker atmospheric bands or belts, where cooler gas sinks, and lighter bands known as zones, where warmer gas rises. The “thin shell” simulation generated cyclones, anticyclones such as those believed to give rise to the large red spot, and zones and belts, also known as zone rays on gas giants such as Jupiter and Saturn.
Now for the really heavy stuff. A planet’s dynamo generates its magnetic field deep inside. The Earth’s dynamo is the constant liquid liquid iron in the outer core (outside the inner core of solid iron), and electric currents are created when electrons flow with it and the energy is transformed into a magnetic field. This is why planets with magnetic fields are assumed to have metallic nuclei. The “thick shell” simulation recreated the way the hydrodynamic layers of gas giants behaving like liquids interact with their magnetic fields. This resulted in convection deep inside the magnetic field that caused it to throw feathers into space. Wherever there was higher magnetic energy, it also created more anticyclones.
There are some differences between the planets. Saturn has a more dangerous atmosphere, so the fluid dynamics behind the storms are more similar to Jupiter’s. This may be because the thicker atmosphere makes it harder to determine if gases are swirling around. Not so many anticyclones seem to happen on Saturn.
Next time you look at the hypnotic vortices of Saturn and Jupiter, remember that behind the beauty there is an animal.