Why the aircraft shudders after hitting air turbulence?

Question

When the aircraft shudders it is scary. Many may not admit it but they do get scared. When the aircrafts hits some air pocket, the fear factor goes double. Why the turbulence has such an effect on the aircraft.

Answer 1

Many passengers do not understand the effects of turbulence, or that an encounter with turbulence may occur without warning.

Turbulence is air movement that normally cannot be seen. It may occur when the sky appears to be clear and can happen unexpectedly. It can be created by any number of different conditions, including atmospheric pressures, jet streams, mountain waves, cold or warm fronts, or thunderstorms.

Different intensities of turbulence

Light turbulence - briefly causes slight, erratic changes in altitude and/or attitude.

Light chop - slight, rapid and somewhat rhythmic bumpiness without noticeable changes in altitude or attitude.

Moderate turbulence - similar to light turbulence, but greater intensity. Changes in altitude/attitude occur. Aircraft remains in control at all times. Variations in indicated air speed.

Moderate chop - similar to light chop, but greater intensity. Rapid bumps or jolts without obvious changes in altitude or attitude.

Severe turbulence - large, abrupt changes in altitude/attitude. Large variation in indicated airspeed. Aircraft may be temporarily out of control.

Extreme turbulence - aircraft is violently tossed about and is impossible to control. May cause structural damage.

The reactions inside aircraft vary from occupants feeling slight strain against their seat belts and unsecured items being slightly displaced, through to occupants being forced violently against seat-belts, and unsecured items being being tossed about. (Imagine what it would be like if you were not wearing a seat belt!)

Answer 2

The vibration that you are refering to is actually the airplane itself flexing.  All aircraft bend and flex in order to handle just this kind of situation.  in effect the wings are flapping and the stress translates into vibration.  the ships are built to take it.  don't worry!