| Deep within the violent Jovian atmosphere towering water and ammonium
hydrosulfide clouds are lit by lightning bolts and weak sunlight gleaming
through a high layer of cirrus clouds of ammonia
crystals. Ammonia crystals refract and reflect the sunlight
to surround the sun with exotic halos. Painting by illustrator
and author Ron Miller, he used HaloSim3 to simulate the NH3
halos (large view). ©Ron
Miller, reproduced with permission.
The highest clouds in
mighty Jupiter's hydrogen/helium atmosphere are a cirrus like layer
of ammonia (NH3) crystals where the pressure is 0.3 - 0.7 bar
and temperatures about -110 C. Solid ammonia has a cubic symmetry
structure and thus could form cloud crystals of similar forms to those
of cubic CO2. Ammonia has a slightly
greater refractive index than CO2 and is transparent. Halos from the
upper Jovian clouds could therefore be very similar indeed to those
predicted for tiny Mars.
and temperatures in Jupiter's atmosphere.
The upper ammonia crystal clouds are likely tiny cubes, octahedra
and cuboctahedra and could form halos similar to those predicted
for CO2 clouds on Mars.
20-30 km deeper there are clouds formed from ammonium hydrosulfide
crystals. They are probably darkened and coloured by sulfurous or
phosphorus polymers and organic compounds. Not enough is known to
predict their halos.
60 km beneath the ammonia cloud layer we find superficially Earthlike
clouds of water molecules. Pressures are 5-6 bar and temperatures
are similar to those of Earth. Their windblown anvils and cirrus push
high into the hydrosulfide layer and their ice crystals could form
Earthlike halos. Their lower levels have liquid droplets and rain
or drizzle warm corrosive ammonium hydroxide solution down into the
In summary, Jupiter's high ammonia cloud layer could form halos from
its octahedral, cuboctahedral or even rhombic dodecahedral crystals
like those predicted for CO2 clouds on Mars . Much deeper, when the
weak sun penetrates through, water-ice cirrus might give glimpses
of Earthlike halos.