Dynamics of Jupiter's Cloud Bands

The observed zonal motion of Jupiter's atmosphere near the cloud tops is investigated assuming geostrophic balance and a systematic temperature difference between light and dark bands. Excellent agreement is obtained between observed velocities and those predicted from the thermal wind relation with the temperature and rotation rate of the deep atmosphere independent of latitude. The light bands are found to be warmer than the dark bands. This model is inconsistent with a monotonic variation of insolation as the only energy source for the flow. The barotropic stability criterion is also applied to the observed motion, and it appears that the necessary criterion for instability is approached but not exceeded in mid-latitude regions.