  Juno Microwave Radiometer (MWR) observations of Jupiter's mid-latitudes
reveal a strong correlation between brightness temperature contrasts and zonal
winds, confirming that the banded structure extends throughout the troposphere.
However, the microwave brightness gradient is observed to change sign with
depth: the belts are microwave-bright in the $p<5$ bar range and microwave-dark
in the $p>10$ bar range. The transition level (which we call the jovicline) is
evident in the MWR 11.5 cm channel, which samples the 5-14 bar range when using
the limb-darkening at all emission angles. The transition is located between 4
and 10 bars, and implies that belts change with depth from being
NH$_3$-depleted to NH$_3$-enriched, or from physically-warm to physically-cool,
or more likely a combination of both. The change in character occurs near the
statically stable layer associated with water condensation. The implications of
the transition are discussed in terms of ammonia redistribution via meridional
circulation cells with opposing flows above and below the water condensation
layer, and in terms of the `mushball' precipitation model, which predicts
steeper vertical ammonia gradients in the belts versus the zones. We show via
the moist thermal wind equation that both the temperature and ammonia
interpretations can lead to vertical shear on the zonal winds, but the shear is
$\sim50\times$ weaker if only NH$_3$ gradients are considered. Conversely, if
MWR observations are associated with kinetic temperature gradients then it
would produce zonal winds that increase in strength down to the jovicline,
consistent with Galileo probe measurements; then decay slowly at higher
pressures.
