On the Earth, the blue color of the sky is caused by the presence of dust particles in the atmosphere which have just the right range of sizes to scatter light more strongly if it is blue than red. Very large dust grains from a volcanic eruption, would tend to absorb and severely scatter light so that the atmosphere would take on a red tinge at all angles above the horizon, even at the zenith in extreme situations.
As for what might be the case on Jupiter, I think this is anyone's guess until we have first hand information about what the composition of the atmosphere really is. The chemistry of the atmosphere is important and there are pretty good constraints to this already. It is almost completely hydrogen and helium...which are colorless gases!
Galileo will certainly turn up some surprises, especially in regards the abundance of water which for years has been expected to be a very important constituent. So far as its dust and aerosol composition is concerned, I think the jury is still out. Until we know exactly the sizes of these possible constituents we cannot really say if they are small enough to cause the right kind of scattering in the upper layers of the atmosphere where sunlight is not severely absorbed. The production of these components is, apparently, a complicated process which I imagine is probably influenced by the temperature of the atmosphere. Jupiter is 50-100 degrees colder than the Earth so I would imagine that at the upper layers of the atmosphere, snowflakes and ice crystals would be the dominant constituent. These are much too large to cause a blue sky. The Jovian sky might be milky white instead.
It is known from spectroscopic studies that the clouds are rich in organic compounds, and these can precipitate out as rain drops at various atmospheric levels. Perhaps these precipitates are what give Jupiter is complex colorations.
Copyright 1997 Dr. Sten Odenwald
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