In 1893, George Francis FitzGerald noted that the upper layers of the atmosphere must be fairly good conductors. JSTOR ( July 2021) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed.įind sources: "Schumann resonances" – news Please help improve this article by adding citations to reliable sources in this section. This section needs additional citations for verification. In geophysical survey, Schumann resonances are used to locate offshore hydrocarbon deposits. Interest in Schumann resonances renewed in 1993 when E.R. Williams showed a correlation between the resonance frequency and tropical air temperatures, suggesting the resonance could be used to monitor global warming. A new field of interest using Schumann resonances is related to short-term earthquake prediction. More recently, discrete Schumann resonance excitation has been linked to transient luminous events - sprites, ELVES, jets, and other upper-atmospheric lightning. Įffects on Schumann resonances have been reported following geomagnetic and ionospheric disturbances. Some have proposed that lightning on other planets might be detectable and studied by means of Schumann resonance signatures of those planets. Schumann resonances have been used to study the lower ionosphere on Earth and it has been suggested as one way to explore the lower ionosphere on celestial bodies. Owing to the connection between lightning activity and the Earth's climate it has been suggested that they may be used to monitor global temperature variations and variations of water vapor in the upper troposphere. Observations of Schumann resonances have been used to track global lightning activity. The peaks exhibit a spectral width of approximately 20% on account of the damping of the respective modes in the dissipative cavity. The higher resonance modes are spaced at approximately 6.5 Hz intervals (as may be seen by feeding numbers into the formula), a characteristic attributed to the atmosphere's spherical geometry. The lowest-frequency mode has the highest intensity, and the frequency of all modes can vary slightly owing to solar-induced perturbations to the ionosphere (which compress the upper wall of the closed cavity) amongst other factors. In the normal mode descriptions of Schumann resonances, the fundamental mode is a standing wave in the Earth–ionosphere cavity with a wavelength equal to the circumference of the Earth. The cavity is naturally excited by electric currents in lightning. The limited dimensions of the Earth cause this waveguide to act as a resonant cavity for electromagnetic waves in the ELF band. Schumann resonances occur because the space between the surface of the Earth and the conductive ionosphere acts as a closed, although variable-sized waveguide. Schumann resonances are the principal background in the part of the electromagnetic spectrum from 3 Hz through 60 Hz, and appear as distinct peaks at extremely low frequencies (ELF) around 7.83 Hz (fundamental), 14.3, 20.8, 27.3, and 33.8 Hz. The global electromagnetic resonance phenomenon is named after physicist Winfried Otto Schumann who predicted it mathematically in 1952. Schumann resonances are global electromagnetic resonances, generated and excited by lightning discharges in the cavity formed by the Earth's surface and the ionosphere. The Schumann resonances ( SR) are a set of spectrum peaks in the extremely low frequency (ELF) portion of the Earth's electromagnetic field spectrum. A diagram of Schumann resonances in Earth's atmosphere
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