 There are three main causes of in-flight rough air. One of them is I suppose the obvious one of just flying through a storm or near a storm but there are some more subtle kinds of turbulence that can affect you on a flight. Actually flying over a mountain range can often be quite bumpy because of the way the air blows over the mountains and there's a third category that's even more subtle. It's invisible, it's called clear air turbulence and it's just generated by fast