[HPsquared]

There isn't much turbulence, wind gusts etc. at altitude - these are more of an effect of the bumpy and uneven, alternative hot and cold surface at ground level - the bumps are usually all smoothed out by the time you are high up in the air.

(besides large storms, of course)

EDIT: Turns out there is sometimes some turbulence at altitude, caused by large mountains, storms and the jet stream - but these are all predictable and avoidable.