The square of the Brunt-Väisälä frequency is negative in this case.

Note that a purely imaginary Brunt-Väisälä frequency results in a flow which is always unstable.

The Brunt-Väisälä frequency is an upper limit for the frequency in actual internal waves.

Above the Brunt-Väisälä frequency, there may be evanescent internal wave motions, for example those resulting from partial reflection.

He independently co-discovered the Brunt-Väisälä frequency.

The packet oscillates at the Brunt-Väisälä frequency:

The Brunt-Väisälä frequency is a closely related quantity that uses potential temperature and is used extensively in investigations of atmospheric stability.

The Brunt-Väisälä frequency relates to internal gravity waves and provides a useful description of atmospheric and oceanic stability.

In the absence of any diffusion whatsoever its behaviour is identical to that involved in the theory of the Brunt-Väisälä frequency (Section 15.4).

In atmospheric dynamics, oceanography, asteroseismology and geophysics, the Brunt-Väisälä frequency, or buoyancy frequency, is the angular frequency at which a vertically displaced parcel will oscillate within a statically stable environment.

The frequencies of these geophysical wave motions vary from a lower limit of the Coriolis frequency (inertial motions) up to the Brunt-Väisälä frequency, or buoyancy frequency (buoyancy oscillations).