Weather systems
Jupiter’s belts and zones are divided from each other along boundaries where strong jets of wind blow alternatingly eastwards and westwards around the planet. Opposing jets on either side of each weather band create sheer forces that twist the features within them in either clockwise or anticlockwise directions. Such features include compact dark spots, elongated ‘barges’ and wave-like structures called ‘festoons’. These all have complex origins that are not fully understood, but many are linked to upwellings of material and interactions between neighbouring regions of high and low air pressure. Storms form at various levels within the atmosphere, often with lightning triggered when the separation of warmer and cooler materials builds up enormous static electric charges.
As on most of the other giant planets, Jupiter’s weather is driven mostly by heat escaping from its interior. The planet emits around twice as much energy as it receives from the Sun. This is due to a combination of residual heat from its formation, ongoing internal contraction and chemical reactions in the deep interior. Convection cells transporting warm fluid to the surface and replacing it with cooler material sinking back down are thought to drive a deep-rooted circulation pattern with consequences we see at the surface. According to this model, the zones represent upwellings of material that pile up to greater heights and form cool, bright clouds on its upper surface. The belts, meanwhile, mark downwelling material where the upper clouds evaporate to expose the deeper, warmer layers.
1 Oval storms
These small white storms roll across the planet, occasionally merging and forming larger redder storms.
2 Equatorial Zone
This zone is one of the more stable regions on Jupiter, without as much activity and with constant wind shear. It’s sometimes bisected by a dark belt.
3 North Temperate Belt
This belt comprises the strongest prograde, or eastward, belt on the planet. It fades once every ten years, causing the surrounding zones to merge.
4 Great Red Spot
Jupiter’s most visible feature, the GRS has been around for hundreds of years at least and is a strong anticyclonic storm that could fit two to three Earths inside it.
5 North Equatorial Belt
One of the most active areas on the planet, it contains short-lived storms in the form of small, white anticyclonic ovals and brownish cyclonic storms.
6 South Equatorial Belt
This belt is usually the planet’s widest and darkest. It sometimes vanishes and reforms from a single white spot that exudes dark material, which is stretched by wind.
7 North polar region
In contrast to the rest of the planet, the poles are dark, blurred areas without much change.
8 Hotspots
Also known as festoons, these greyish-blue spots are a bit of a mystery. There are few clouds here, allowing heat to escape from the gas layer below.
9 South polar region
Like the north polar region, this area on Jupiter appears to be mostly featureless.