Väisälä period

Väisälä period

[′väl·sä·lä ‚pir·ē·əd]
(acoustics)
The natural period of oscillation of a small parcel of air which is displaced adiabatically in a vertical direction, in an isothermal atmosphere horizontally stratified by gravity; equal to 337 seconds for a sound velocity of 333 meters per second.