Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Moist convection in hydrogen atmospheres and the frequency of Saturn’s giant storms


A giant storm erupted on Saturn in December 2010. It produced intense lightning and cloud disturbances and encircled the planet in six months. Six giant storms—also called Great White Spots—have been observed on Saturn since 1876, recurring every 20 to 30 years and alternating between mid-latitudes and the equator. Here we use thermodynamic arguments to demonstrate that the quasi-periodic occurrence of Saturn’s giant storms can be explained by a water-loading mechanism, in which moist convection is suppressed for decades owing to the relatively large molecular weight of water in a hydrogen–helium atmosphere. We find that the interaction between moist convection and radiative cooling in the troposphere above the cloud base produces an oscillation that leads to giant storm generation with a period of approximately 60 years for either mid-latitudes or the equator, provided the mixing ratio of water vapour in the troposphere exceeds 1.0%. We use a two-dimensional axisymmetric dynamic model and a top-cooling convective adjustment scheme to apply our conceptual model to Saturn. For a water vapour mixing ratio of 1.1%, simulated storms show a recurrence interval, ammonia depletion and tropospheric warming that are consistent with 2010 observations. Jupiter’s atmosphere is more depleted in water than Saturn, which may explain its lack of planet-encircling storms.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Virtual temperature of moist adiabats.
Figure 2: Thermodynamic diagram for Saturn’s atmosphere.
Figure 3: Residual azimuthal wind and temperature anomaly after the geostrophic adjustment.
Figure 4: Time evolution of the ammonia vapour mixing ratio and the streamfunction.
Figure 5: Evolution of Saturn’s atmospheric temperature and minor constituents.


  1. Sanchez-Lavega, A. Saturn’s Great White Spots. Chaos 4, 341–353 (1994).

    Article  Google Scholar 

  2. Sanchez-Lavega, A. & Battaner, E. The nature of Saturns atmospheric Great White Spots. Astron. Astrophys. 185, 315–326 (1987).

    Google Scholar 

  3. Sayanagi, K. M. et al. Dynamics of Saturn’s Great Storm of 2010–2011 from Cassini ISS and RPWS. Icarus 223, 460–478 (2013).

    Article  Google Scholar 

  4. Sanchez-Lavega, A. et al. Deep winds beneath Saturn’s upper clouds from a seasonal long-lived planetary-scale storm. Nature 475, 71–74 (2011).

    Article  Google Scholar 

  5. Fischer, G. et al. A giant thunderstorm on Saturn. Nature 475, 75–77 (2011).

    Article  Google Scholar 

  6. Achterberg, R. K. et al. Changes to Saturn’s zonal-mean tropospheric thermal structure after the 2010–2011 northern hemisphere storm. Astrophys. J. 786, 92–100 (2014).

    Article  Google Scholar 

  7. Janssen, M. A. et al. Saturn’s thermal emission at 2.2-cm wavelength as imaged by the Cassini RADAR radiometer. Icarus 226, 522–535 (2013).

    Article  Google Scholar 

  8. Laraia, A. L. et al. Analysis of Saturn’s thermal emission at 2.2-cm wavelength: Spatial distribution of ammonia vapor. Icarus 226, 641–654 (2013).

    Article  Google Scholar 

  9. Dyudina, U. A. et al. Lightning storms on Saturn observed by Cassini ISS and RPWS during 2004–2006. Icarus 190, 545–555 (2007).

    Article  Google Scholar 

  10. Stoker, C. R. Moist convection—a mechanism for producing the vertical structure of the Jovian equatorial plumes. Icarus 67, 106–125 (1986).

    Article  Google Scholar 

  11. Hueso, R. & Sanchez-Lavega, A. A three-dimensional model of moist convection for the giant planets II: Saturn’s water and ammonia moist convective storms. Icarus 172, 255–271 (2004).

    Article  Google Scholar 

  12. Guillot, T. Condensation of methane, ammonia, and water and the inhibition of convection in giant planets. Science 269, 1697–1699 (1995).

    Article  Google Scholar 

  13. Sugiyama, K. et al. Intermittent cumulonimbus activity breaking the three-layer cloud structure of Jupiter. Geophys. Res. Lett. 38, 201–206 (2011).

    Article  Google Scholar 

  14. Sugiyama, K., Nakajima, K., Odaka, M., Kuramoto, K. & Hayashi, Y. Y. Numerical simulations of Jupiter’s moist convection layer: Structure and dynamics in statistically steady states. Icarus 231, 407–408 (2014).

    Article  Google Scholar 

  15. Emanuel, K. A. Atmospheric Convection (Oxford Univ. Press, 1994).

    Google Scholar 

  16. Orton, G. S. & Ingersoll, A. P. Saturn’s atmospheric temperature structure and heat budget. J. Geophys. Res. 85, 5871–5881 (1980).

    Article  Google Scholar 

  17. Asplund, M., Grevesse, N., Sauval, A. J. & Scott, P. The chemical composition of the Sun. Annu. Rev. Astron. Astrophys. 47, 481–522 (2009).

    Article  Google Scholar 

  18. Fletcher, L. N. et al. Sub-millimetre spectroscopy of Saturn’s trace gases from Herschel/SPIRE. Astron. Astrophys. 539, A44 (2012).

    Article  Google Scholar 

  19. Fletcher, L. N., Orton, G. S., Teanby, N. A., Irwin, P. G. J. & Bjoraker, G. L. Methane and its isotopologues on Saturn from Cassini/CIRS observations. Icarus 199, 351–367 (2009).

    Article  Google Scholar 

  20. Fletcher, L. N., Orton, G. S., Teanby, N. A. & Irwin, P. G. J. Phosphine on Jupiter and Saturn from Cassini/CIRS. Icarus 202, 543–564 (2009).

    Article  Google Scholar 

  21. Niemann, H. B. et al. The Galileo probe mass spectrometer: Composition of Jupiter’s atmosphere. Science 272, 846–849 (1996).

    Article  Google Scholar 

  22. Lindal, G. F., Sweetnam, D. N. & Eshleman, V. R. The atmosphere of Saturn—an analysis of the Voyager radio occultation measurements. Astronom. J. 90, 1136–1146 (1985).

    Article  Google Scholar 

  23. Fletcher, L. N. et al. Thermal structure and dynamics of Saturn’s northern springtime disturbance. Science 332, 1413–1417 (2011).

    Article  Google Scholar 

  24. Emanuel, K. A., Neelin, J. D. & Bretherton, C. S. On large-scale circulations in convecting atmospheres. Q. J. R. Meteorol. Soc. 120, 1111–1143 (1994).

    Article  Google Scholar 

  25. Charney, J. G. & Eliassen, A. On the growth of the hurricane depression. J. Atmos. Sci. 21, 68–75 (1964).

    Article  Google Scholar 

  26. LeVeque, R. J. Finite Difference Methods for Ordinary and Partial Differential Equations: Steady-State and Time-Dependent Problems (Society for Industrial and Applied Mathematics, 2007).

    Book  Google Scholar 

  27. Shu, C. W. & Osher, S. Efficient implementation of essentially non-oscillatory shock-capturing schemes. J. Comput. Phys. 83, 32–78 (1989).

    Article  Google Scholar 

  28. Roe, P. L. Approximate Riemann solvers, parameter vectors, and difference schemes. J. Comput. Phys. 135, 250–258 (1997); (Reprinted from the J. Comput. Phys. 43, 357–372 (1981)).

    Article  Google Scholar 

  29. Shu, C. W. Total-variation-diminishing time discretizations. SIAM J. Sci. Stat. Comp. 9, 1073–1084 (1988).

    Article  Google Scholar 

Download references


This research was supported by the National Science Foundation, award number AST-1109299, and by the Cassini Project of NASA. We thank D. Yang for discussions on moist convection.

Author information

Authors and Affiliations



Both authors participated equally in formulating the model and interpreting the final results. C.L. wrote the code for the numerical model and convective adjustment scheme.

Corresponding author

Correspondence to Cheng Li.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 4132 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Li, C., Ingersoll, A. Moist convection in hydrogen atmospheres and the frequency of Saturn’s giant storms. Nature Geosci 8, 398–403 (2015).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing