system
Given the following post, respond as if you're commenting on Reddit:
human
Why isn't the atmosphere of Jupiter homogeneous?

After what I would assume is a few billion years of mixing, why are there still such defined patterns in Jupiter's atmosphere? Why are the layers not homogeneous? Does it have to do with updrafts mixing more dense layers?
gpt
Heavier gases tend to get to deeper layers, what you would expect with no activity is an equilibrium that doesn't have a homogeneous mixture, but heavier gases in deeper layers.

Jupiter's interior is still hot, while the outside is cooled by radiation (to space). In addition there is the "daily" cycle of sunlight. That leads to temperature gradients, and that leads to convection. Convection mixes up the different atmospheric layers in many individual cells and generates patterns in the atmosphere. There are many more things (interaction with the magnetic field, for example), but convection alone prevents an atmosphere in equilibrium.