How does the speed of sound change with changing altitude in International Standard Atmosphere (ISA) conditions? As the altitude increases, the speed of sound...
Because air is compressible the changing air pressure created by the movement of the airplane is accompanied by a change of air temperature and a change of air density. Owing to this, the speed of movement generated by the pressure wave is equal to the speed of sound. Sound waves are audible pressure waves travelling at the speed of sound.
The Local Speed of Sound is defined by:
LSS=38.95∗√(T(K))
The speed of propagation of small pressure waves depends upon the temperature of the air ONLY.
In the troposphere, as altitude increases, the temperature decreases, therefore the LSS also decreases.
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