The “Musical” Sound Emitted by a Tornado

Abstract

This paper attempts to explain the "whining" or "hissing" sound reported from tornadoes. pothesis is that the air masses involved in the tornado circulation execute some free vibrations. these vibrations may be in the audible range for a small vortex whose radius is of the order of 10 m. or less. formula is obtained which relates the frequency of the tone to the inner radius of the vortex. to experimental verification.

Low-Frequency Atmospheric Acoustic Energy Associated with Vortices Produced by Thunderstorms

“…This unique dataset permitted comparisons between the measured acoustic signatures and sound generation models. The dominant frequencies closely matched those predicted by Abdullah (1966) for the radial modes of vibration of vortices. It will also be valuable to apply fully compressible models to explore the sound generated by a variety of fluid dynamic processes.…”

“…20. These models are the radial-modesof-vibration model of Abdullah (1966), the tornado/ boundary interaction model of Tatom et al (1995), and the corotating vortex model (Powell 1964;Mitchell et al 1992). The infrasonic data seemed most consistent with the model of Abdullah, as is shown in a later section.…”

“…The infrasonic data seemed most consistent with the model of Abdullah, as is shown in a later section. Abdullah (1966) found expressions for the fundamental (F0) and first harmonic (F1) of the vibrational modes in Hertz to be F0 ϭ ͩ …”

“…Values have been weighted by multiplying by the square of the dimensionless correlation coefficient to emphasize the spectra of higher-quality signal data. Thompson (1910) Vortex vibrations Realistic model Lamb (1945) Review of past work on vortex vibrations and waves Powell (1964) Theory of vortex sound Anderson and Freier (1965) Tornado wave motion Abdullah (1966) Tornado radial mode vibrations as a sound source Focused on audible detection Colgate and McKee (1969) Electrostatic sound Dessler (1973) Electrostatic sound Meecham (1971) Turbulence Comparative review of generation processes Concluded vortex sound processes were most likely Few (1979) Lightning Lyamshev and Skvortsov (1988) Review of vortex sound mechanisms Kozel et al (1992) Vortex wave effects Mitchell et al (1992) Sounds from corotating vortices Numerical model showing evolution of the system Tatom et al (1995) Seismic waves from tornado-surface interactions Suggested the basis for a detection system FIG. 20.…”

“…The multiple-core characteristic frequency estimates were made using the assumption of two corotating vortices. This table shows that the mechanism of Abdullah (1966) produces sound in the frequency range of our observations and suggests that a limited range of frequencies will occur for a considerable range of vortex properties. Corotating vortices will tend to produce sound at significantly lower frequencies (typically, less than 0.1 Hz) than those focused on here.…”