We know that Sound Waves are Longitudinal Waves...
But still while drawing diagrams to show wavelength,amplitude,timbre etc.
we show the sound wave as a transverse wave in the diagram ?
why we do that ?
Sound waves are always longitudinal in nature. They are represented by compressions and rare fractions of oscillating particles. When we show the amplitude, wavelength, etc of a sound wave, we are not drawing the actual sound wave but a depiction in form sine wave. This is done because of ease of understanding.
A actual sound wave and its sinusoidal depiction is shown below for your understanding.
Hope this clears your doubts.
While sound itself is a longitudinal wave, the transverse graph is actually the movement of a particular column of air.
You must have read that in a wave, the medium does not move but the energy gets transferred. The particles move to and fro with respect to their positions. The transverse graph represents that to and fro movement of the particles.
JUST found this info about my own ques.
Hope this helps !