Jupiter radiates 1.6 times as much energy as falls on it from the Sun.  Thus, Jupiter has an internal heat source.  It is thought that much of this heat is residual heat left over from the original collapse of the primordial nebula to form the Solar System, but some may come from slow contraction (liquids are highly incompressible, so Jupiter cannot be contracting very much.)  This internal heat source is presumably responsible for driving the complex weather pattern in its atmosphere, unlike the Earth where the primary heat source driving the weather is the Sun.