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Internal waves produced by a convective layer

Published online by Cambridge University Press:  28 March 2006

A. A. Townsend
A. A. Townsend
Affiliation:
Emmanuel College, Cambridge
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Abstract

Fluid impacts on the base of a stably stratified region of fluid cause internal-wave ripples whose spread is predominantly horizontal if the duration of the impacts is long compared with the natural period of the stratified fluid. The development of a single ripple in a slightly viscous fluid is calculated, first with a constant vertical gradient of potential density and then with a gradient varying linearly with height. The single-ripple results are used to find the intensity of the statistically steady wave motion generated by impacts which are randomly distributed in space and time. Above a critical height, dependent on the viscosity and stability of the fluid and on the time and length scales of the impacts, wave energy falls off as the −5/3 power of the height with a constant density gradient and as the −25/6 power with a linearly varying gradient. The predictions are compared with observations of temperature fluctuations in the stable region of an ice-water convection system and with observations of ‘clear-air turbulence’ over strato-cumulus cloud. Reasonable numerical agreement can be obtained with plausible values for the scales of the convective motion which provides the impacts.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 24 , Issue 2 , February 1966 , pp. 307 - 319
Copyright
© 1966 Cambridge University Press

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References

James, D. G. 1959 Quart. J. Roy. Met. Soc. 85, 12.
Lamb, H. 1932 Hydrodynamics, p. 378. Cambridge University Press.
Moore, J. G. 1964 Met. Office Scientific Paper, no. 19. H.M.S.O.
Priestley, C. H. B. 1959 Turbulent transfer in the lower atmosphere. University of Chicago Press.
Townsend, A. A. 1959 J. Fluid Mech. 5, 20.
Townsend, A. A. 1964 Quart. J. Roy. Met. Soc. 90, 24.