I was a flight attendant for over 20 years. You would not believe how many times I had to tell MEN to fasten their seatbelt when we were going through turbulence or getting ready to hit unstable areas. Oh, they sure showed me when they would unfasten it when I was gone.
Turbulence is invisible and we would hit it going about 600 miles an hour. I have been severely injured from clear air turbulence, dropping 1000 feet and bouncing between the floor and ceiling.
In a way turbulence is good news. It means you are moving forward and have lift(at least that is what I keep telling myself). Airlines have done a pretty good job changing routes and altitude to avoid these problems somewhat. I wonder how long the severe turbulence lasted? Sometimes it is only a couple huge bumps and then back to smooth. Those are the ones that get ya.