Answer to Question 1
Jupiter's atmosphere is a very thin layer of turbulent gas above a liquid interior, separated by various bands and zones with circulating storms. The clouds form dark belts and light zones that circle the planets like the stripes on a child's ball. This form of atmospheric structure is called beltzone circulation. The belts are dark bands of clouds while the zones are bright bands of clouds. The zones are high, cold regions of ammonia ice crystals, white in color. But the lower, warmer belts are brownish from complex chemistry involving hydrogen sulfide, ammonia, and other chemicals.
Answer to Question 2
Ganymede is exposed to two unusual processes that many worlds never experience. Tidal heating, the frictional heating of a body by changing tides, could have heated Ganymede's interior and added to the heat generated by radioactive decay.
The second process that affects Ganymede is the inward focusing of meteorites. You should expect such a moon to have lots of craters, but the bright terrain on Ganymede has few craters. That part of Ganymede's surface must be only about 1 billion years old.
These unusual processes are caused by Ganymede's close orbit to Jupiter,
Percussion Patterns, Right Lateral Thorax
Uranus's aurorae against its equatorial rings, imaged by the Hubble telescope. Unlike the auror
Lo, Jupiter
Jupiter’s Magnetosphere
Solar EM Radiation Penetration into Earth's Atmosphere
What are examples of ideal forms?