 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 air