Jupiter’s weather makes Earth’s most violent hurricanes look gentle. The planet hosts winds that top 600 kilometers per hour, storms larger than our entire planet, lightning bolts that dwarf anything in our skies, and a form of hail made not of water ice but of ammonia slush. Because Jupiter has no solid surface, its “weather” is really just layers upon layers of atmosphere in constant, turbulent motion, stretching thousands of kilometers deep. What the Juno spacecraft and decades of ground-based observation have revealed is a world where familiar meteorological processes play out at scales and in chemical conditions that would be unrecognizable to any earthly forecaster.
Winds That Run Deep
The most obvious feature of Jupiter’s weather is its banded appearance. Those alternating light zones and dark belts are the visible expression of powerful jet streams that race around the planet in alternating directions, east and west. At the cloud tops, these winds reach speeds of several hundred meters per second. When NASA’s Galileo probe parachuted into Jupiter’s atmosphere in 1995, it measured zonal winds increasing from roughly 80 meters per second near the visible cloud deck to about 180 meters per second at the 5-bar pressure level, where they stayed approximately constant as far down as the probe survived.1New Astronomy Reviews. The Galileo probe: how it has changed our understanding of Jupiter That was about 132 kilometers below the 1-bar reference level, and the winds showed no sign of dying off.
Juno’s gravity measurements have since confirmed that these jets are not a thin skin phenomenon. Analysis of Jupiter’s high-degree gravity field shows that the surface wind pattern extends into the planet’s interior to a depth of roughly 2,500 kilometers, and the amplitude of the deep flow closely matches the surface winds at that depth.2The Astrophysical Journal. Strong Resemblance between Surface and Deep Zonal Winds inside Jupiter Revealed by High-degree Gravity Moments At shallower truncation depths, the deep winds appear even stronger than the surface ones. The picture that has emerged is of jet streams anchored deep in a fluid interior, not weather patterns generated only near the cloud tops. Stable layers within the atmosphere may affect how fast these winds decay with depth, making the vertical structure harder to pin down than models that assume a simple, uniformly mixed atmosphere would suggest.3Monthly Notices of the Royal Astronomical Society. Implications of a stable layer on the vertical structure of jet streams on Jupiter
The Great Red Spot and Other Vortices
Jupiter’s Great Red Spot is the most famous storm in the solar system, a swirling anticyclone wider than Earth that has persisted for centuries. For a long time, nobody knew how deep it went. Was it just a thin eddy at the cloud tops, or did it have roots reaching far below? Juno answered that question from two independent angles. Gravity measurements during close overflights constrained the Great Red Spot to the upper 500 kilometers of the atmosphere.4PubMed. The depth of Jupiter’s Great Red Spot constrained by Juno gravity overflights Meanwhile, Juno’s Microwave Radiometer probed the spot and other vortices directly and found roots extending deeper than the altitude where water is expected to condense, along with density inversion layers beneath them.5PubMed. Microwave observations reveal the deep extent and structure of Jupiter’s atmospheric vortices
Five hundred kilometers might not sound like much on a planet with a radius of nearly 70,000 kilometers, but it is enormous compared to Earth’s deepest weather systems, which barely scratch 15 kilometers in height. And unlike terrestrial hurricanes, which need warm ocean water to survive and quickly die over land, the Great Red Spot has no surface to disrupt it. Its persistence, compared with the chaotic life cycle of storms on Earth, reflects a fundamental difference: on a planet with no solid ground and very little external forcing from seasons, large vortices can settle into stable states and endure for decades or longer.6Planetary Climates. Jupiter Winds and Weather
Geometric Cyclones at the Poles
Before Juno, nobody had a clear look at Jupiter’s poles. What the spacecraft found there was startling. At each pole, a central cyclone sits surrounded by a ring of smaller cyclones arranged in a geometric pattern: eight cyclones forming an octagon around the north pole and five (sometimes six) forming a pentagon around the south pole. These patterns have stayed almost completely stable over the years Juno has been watching.
Five years of infrared imaging show that the cyclones drift slightly around what appear to be equilibrium positions, with oscillation timescales of a few months, but the overall structures remain intact.7Journal of Geophysical Research: Planets. Five Years of Observations of the Circumpolar Cyclones of Jupiter Change is rare. In 2019, a sixth cyclone briefly joined the southern pentagon, but it disappeared after about two months without merging with any of the existing storms.8Geophysical Research Letters. Oscillations and Stability of the Jupiter Polar Cyclones The creation or disappearance of one of the permanent cyclones has never been observed. Why they lock into these specific geometric arrangements, and what keeps interlopers from joining permanently, remains an active area of research.
Lightning, Ammonia, and Mushball Hail
Jupiter has thunderstorms, and they produce lightning. That much has been known since the Voyager flybys in 1979. But Juno revealed something unexpected: some lightning flashes originate much higher than they should. On Earth, lightning requires liquid water droplets and ice particles colliding inside a cloud. On Jupiter, the main water clouds form at pressures around 5 to 6 bars, well below the visible ammonia cloud deck. Yet Juno detected small lightning flashes originating above the 2-bar pressure level, where temperatures are far too cold for pure liquid water to exist.9PubMed. Small lightning flashes from shallow electrical storms on Jupiter
The explanation involves ammonia acting as a kind of antifreeze. When ammonia vapor mixes with water ice at high altitudes, it can create a liquid ammonia-water solution at temperatures well below the normal freezing point of water. Modeling shows that this process can generate charge separation and lightning even at shallow altitudes, while also producing lightning at deeper pressures below the water cloud base.10Journal of Geophysical Research: Planets. Lightning Generation in Moist Convective Clouds and Constraints on the Water Abundance in Jupiter Jupiter’s lightning, then, relies on at least two distinct mechanisms operating at different altitudes, which is quite different from the single-mechanism story on Earth.
The ammonia-water interaction also produces one of Jupiter’s strangest weather phenomena: mushballs. Inside powerful thunderstorms, updrafts loft water ice to high altitudes where it encounters ammonia gas and forms a slushy liquid coating. These slushy particles grow by sweeping up more material as they fall, much like hailstones grow inside terrestrial thunderstorms. The resulting objects, dubbed mushballs, are hail-like particles made of ammonia-water slush surrounding a core of ammonia-rich ice.11Journal of Geophysical Research: Planets. Storms and the Depletion of Ammonia in Jupiter: I. Microphysics of “Mushballs”
As mushballs fall, they plunge deep into the atmosphere before evaporating, delivering their ammonia payload far below the water cloud base, to pressures of 5 to 27 bars. Because ammonia tends to concentrate in the mushball’s core, it gets carried even deeper than the water component. This process explains a puzzle that had dogged researchers for years: Juno’s microwave observations showed that ammonia is depleted in Jupiter’s upper atmosphere across broad swaths of the planet, far more so than simple condensation could account for. Mushball transport provides a mechanism for stripping ammonia out of the upper atmosphere and sequestering it at depth.12Journal of Geophysical Research: Planets. Storms and the Depletion of Ammonia in Jupiter: II. Explaining the Juno Observations
What Gives Jupiter Its Colors
Jupiter’s cloud tops are made primarily of ammonia ice, which is white. The deeper water clouds are also not especially colorful. So where do the rich golds, oranges, and reds come from, especially in the belts and the Great Red Spot? The answer involves a still-unidentified chemical compound, often called a chromophore, that absorbs blue light and gives the clouds their warm tones.
Research using ground-based spectroscopy from the Very Large Telescope tested whether a single color-carrying compound could explain all the red coloring across Jupiter’s atmosphere. The results showed that both the belts and the Great Red Spot can be modeled using the same chromophore, though its absorption characteristics differ somewhat from the leading laboratory candidates proposed so far.13Icarus. Colour and tropospheric cloud structure of Jupiter from MUSE/VLT: Retrieving a universal chromophore The idea of a “universal chromophore” is appealing because it simplifies the picture enormously: one compound, distributed unevenly, could account for the entire palette. But pinning down exactly what that compound is has proven difficult. Candidates include sulfur-bearing molecules and organic compounds produced by ultraviolet radiation acting on simple chemicals in the upper atmosphere. The identity of Jupiter’s mystery colorant remains one of the more stubborn open questions in planetary science.
Hot Spots and Windows Into the Deep
Scattered along Jupiter’s North Equatorial Belt are features called hot spots: small regions that appear bright at 5-micron infrared wavelengths because they are relatively clear of clouds, letting heat from the deeper atmosphere shine through. The Galileo probe happened to descend through one of these hot spots, which is partly why it measured an atmosphere drier than expected. These are not “hot” in the sense of being locally heated; they are windows, gaps in the cloud cover that reveal the warmer layers below.
Hot spots are not randomly placed. They appear in a roughly regular chain around the planet, spaced at intervals that correspond to a wavenumber typically between 8 and 12, and they drift westward at speeds of 97 to 113 meters per second depending on their spacing.14Journal of Geophysical Research: Planets. Phase dispersion relation of the 5‐micron hot spot wave from a long‐term study of Jupiter in the visible This pattern strongly suggests they are created by an atmospheric wave. Simulations reproduce their properties well using equatorial Rossby waves: large-scale wave patterns in a rotating atmosphere that create local regions of sinking air. Where air sinks, clouds evaporate and the view clears, producing the hot spot.15PubMed. Nonlinear simulations of Jupiter’s 5-micron hot spots The simulated structures are long-lived, equatorially confined, and periodically spaced, matching the observations closely.
A Stratospheric Heartbeat
Jupiter’s weather is not limited to the troposphere where clouds and storms live. Higher up, in the stratosphere, the planet exhibits a rhythmic oscillation in temperature and wind direction that has been tracked for decades. Called the quasi-quadrennial oscillation, or QQO, it involves alternating bands of eastward and westward winds that propagate downward through the equatorial stratosphere with a period of roughly four to six years.16The Astrophysical Journal. Jupiter’s Equatorial Quasi-quadrennial Oscillation Forced by Internal Thermal Forcing
Earth has something analogous, called the quasi-biennial oscillation, in its own equatorial stratosphere. On Jupiter, mid-infrared observations from the ground tracked roughly two full cycles of the QQO between 2012 and 2019, finding a smooth sinusoidal pattern with a period of about four years and temperature swings of around 7 degrees Kelvin at the 13.5-millibar level. Then, in 2017, something disrupted the pattern. The phase shifted backward by about a year, coinciding with an unusually warm anomaly at 28 degrees north latitude moving westward through the upper stratosphere.17Icarus. Vertically-resolved observations of Jupiter’s quasi-quadrennial oscillation from 2012 to 2019 What caused that disruption is still debated.
The QQO also appears to influence weather features far from the equator. Observations spanning nearly three decades show that the amplitudes of stratospheric planetary waves, particularly at around 20 degrees north latitude, fluctuate in step with the QQO. As the oscillation shifts wind shear patterns, it modifies the vertical channels through which waves can propagate, effectively turning the wave activity up and down on a multi-year cycle.18Journal of Geophysical Research: Planets. Long‐Term Variations of Jupiter’s Stratospheric Planetary Waves Modulated by the Quasi‐Quadrennial Oscillation Jupiter’s stratosphere, far from being a quiet layer above the action, has its own dynamic weather cycle that interacts with the turbulence below.
Auroral Heating and the Energy Puzzle
Jupiter’s upper atmosphere is far hotter than it should be if sunlight were the only energy source. The Galileo probe measured temperatures reaching about 900 Kelvin high in the thermosphere, and models suggest polar regions can reach 1,200 Kelvin or higher depending on magnetospheric activity.19Journal of Geophysical Research: Planets. Jupiter Thermospheric General Circulation Model (JTGCM): Global structure and dynamics driven by auroral and Joule heating The extra heat comes largely from Jupiter’s interaction with its own magnetosphere. Charged particles spiraling along magnetic field lines slam into the polar atmosphere, producing spectacular auroras and dumping energy in the form of Joule heating and particle bombardment.
The interesting meteorological question is how that polar heat spreads to lower latitudes. Thermospheric models show strong horizontal winds of 0.5 to 1.2 kilometers per second at ionospheric heights, carrying heat and atomic hydrogen equatorward. Recent observations suggest that following a solar wind compression event, a pulse of heating can travel from the auroral zone toward lower latitudes at velocities comparable to traveling ionospheric disturbances on Earth.20Geophysical Research Letters. Sub‐Auroral Heating at Jupiter Following a Solar Wind Compression In other words, the solar wind, despite Jupiter’s enormous distance from the Sun, can still alter the planet’s upper-atmospheric energy balance on a global scale. The thermosphere of Jupiter is not just hot; it is highly variable and closely tied to space weather.
When Objects Hit the Atmosphere
Jupiter’s massive gravity makes it a magnet for comets and asteroids, and these impacts create their own transient weather events. The most famous was the collision of Comet Shoemaker-Levy 9 in 1994, which left dark scars visible for months. Smaller impacts happen more frequently and have been captured on camera by amateur astronomers. Simulations of these events show a characteristic sequence: the impactor is compressed and flattened by aerodynamic forces as it plunges into the atmosphere, a process called pancaking. It then breaks apart, typically around the 3-millibar pressure level, and the debris spreads horizontally while the organized shock system behind the object collapses into turbulent flow.21Astronomy & Astrophysics. Impact flux on Jupiter: From superbolides to large-scale collisions
For large enough impactors, the energy deposited into the atmosphere creates temporary disturbances in temperature, composition, and cloud structure that can persist for weeks. These events provide a kind of natural experiment, injecting material and energy at known altitudes and letting researchers watch how Jupiter’s atmosphere responds. The planet absorbs these blows with remarkable resilience; even the massive Shoemaker-Levy 9 scars eventually faded as the atmosphere mixed the debris away, a testament to the relentless churning of Jovian weather.