What causes turbulence?

When the plane goes through clouds is when I notice it. Both departing and landing.

Turbulence

Hydraulics – the haphazard secondary motion caused by eddies within a moving fluid.

Meteorology – irregular motion of the atmosphere, as that indicated by gusts and lulls in the wind.

Eating beans. Oh, wait that is flat ulence. My bad.

forgetting a woman’s birthday or valentines

“Atmospheric scientists define “turbulence” as “a state of fluid flow in which the instantaneous velocities exhibit irregular and apparently random fluctuations.”

Those “irregular fluctuations” of the air create the bumps.”

Source