arXiv2026
Sprawling, turbulent cloud formations dominate the meteorology of Jupiter's mid-to-high latitudes, known as Folded Filamentary Regions (FFRs). A multi-wavelength characterisation by Juno reveals the spatial distribution, vertical structure, and energetics of the FFRs. The cloud tops display multiple lobes of stratiform aerosols, separated by darker, cloud-free lanes, and embedded with smaller eddies and high-altitude cumulus clouds. These cyclonic FFRs are microwave-bright in shallow-sounding wavelengths ($p<5$ bars) and microwave-dark in deep-sounding wavelengths ($p>10$ bars), with the transition potentially associated with the water condensation layer (6-7 bars). Associating microwave contrasts with temperature anomalies, this implies despinning of cyclonic eddies above/below their mid-planes. Despite deep roots (being detectable in wavelengths sounding $\sim100$ bars), they are ``pancake vortices'' with horizontal extents at least an order of magnitude larger than their depth. In the northern hemisphere, FFRs are most common in cyclonic belts poleward of $40^\circ$N (all latitudes are planetocentric), particularly a North Polar Filamentary Belt (NPFB) near $66-70^\circ$N that defines the transition from organised belts/zones to the chaotic polar domain. This distribution explains the high lightning rates from $45-80^\circ$N, peaking in a belt poleward of $52.3^\circ$N, which may trace the availability of water for moist convection. Many observed lightning flashes can be associated to specific FFRs containing bright storms, but some FFRs display no activity, suggesting quiescent periods during storm evolution. Analogies to Earth's oceanic eddies suggest that cyclones deform isentropic surfaces at their midplanes, raising deep water-rich layers upwards to promote moist convection, release latent heat, and inject clouds into the upper troposphere.