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Buoyancy frequency is the frequency with which a parcel or particle of fluid displaced a small vertical distance from its equilibrium position in a stable environment will oscillate. This concept, also termed the Brunt–Väisälä frequency, can apply to a liquid or gaseous medium. The parcel will oscillate in simple harmonic motion with an angular frequency defined by:
where g is the gravitational acceleration, θ is the potential temperature, α is the thermal expansion coefficient, and β is the saline contraction coefficient. In practice, the equivalent formula:
is often used, where c is the velocity of sound, although care must be taken to consistently evaluate ρ and c.
- Physical Oceanography Index
- J. S. Turner. Buoyancy Effects in Fluids. Cambridge Univ. Press, 1973.
- Trevor McDougall, Steve Thorpe, and Carl Gibson. Small-scale turbulence and mixing in the ocean: a glossary. In J. Nihoul and B. Jamart, editors, Small-Scale Turbulence and Mixing in the Ocean, pages 3-9. Elsevier, 1987.