Schumann response

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As Schumann resonance (named after the German physicist and electrical engineer Winfried Otto Schumann ) refers to the phenomenon that electromagnetic waves of certain frequencies along the circumference of the earth standing waves form. The sufficiently conductive earth's surface (mostly salt water ) and the highly conductive ionosphere above it limit a spherical-shell- shaped cavity resonator , from the dimensions of which possible resonance frequencies can be calculated. These can be excited by lightning , but are of such a low amplitude that they can only be detected with very sensitive instruments.

Calculation of the frequencies

The mean circumference of the earth is a = 39,985,427 m (at the equator 40,075 km, polar circumference 39,940 or 40,007.863 km). With a speed of propagation of light of c = 299,792,458 m / s (in a vacuum), this arithmetically results in c / a = 7.5 Hz for the lowest frequency for the mean circumference of the earth. For a cavity resonator with ideally conductive walls, more precise calculations (see literature: Jackson, Elektrodynamik ) lead to the formula:

for the nth frequency (with n = 1, 2, 3 ...).

Since the earth has no ideal conductive walls, the above formula must be multiplied by 0.78 for the observed values ​​and then leads to 7.83 ( fundamental ), 14.3 for n = 1, 2, 3 ... 20.8; 27.3 and 33.8 Hz. Due to dispersion , ionospheric effects and other non-ideal properties of the system, the measured values ​​deviate slightly from the theoretical values ​​and fluctuate depending on the seasons . Schumann resonance frequencies from 3 Hz to 30 Hz belong to the frequency range that is internationally known as Extremely Low Frequency .

Suggestion

By lightning and other operations will be in the atmosphere of the ionosphere and a wide range of electromagnetic waves emitted, also called Sferics be called. Low-frequency waves mainly propagate in the poorly conductive atmosphere between the earth and the ionosphere, both of which are sufficiently good electrical conductors. Waves that are in the same phase again after having circumnavigated the earth (i.e. the circumference of the earth is an integral multiple of the wavelength ) are amplified, others cancel each other out. This results in a lowest resonance frequency averaging around 7.8 Hz.

discovery

The phenomenon was discovered in 1952 by Winfried Otto Schumann and Herbert L. König and investigated experimentally in 1960. The existence of such resonances had already been postulated earlier and a. been described by Nikola Tesla , although he was unable to classify them systematically. In a series of articles between 1952 and 1957, Schumann treated the phenomenon further , taking into account the damping and excitation of the resonances by lightning.

The electromagnetic waves are easily obscured locally by artificially generated alternating fields . When measuring the frequency spectrum in this low-frequency range, one can also observe stronger artificially generated waves, e.g. B. the frequencies of the European and American power grids (50 Hz and 60 Hz) and American and Russian submarine communication systems (76 Hz and 82 Hz).

See also

literature

Web links

Individual evidence

  1. ↑ Can Resonant Oscillations of the Earth Ionosphere Influence the Human Brain Biorhythm? - VD Rusov, Department of Theoretical and Experimental Nuclear Physics, Odessa National Polytechnic University, Ukraine
  2. ^ The electrical nature of storms By DR MacGorman, WD Rust, W. David Rust. Page 114.
  3. ↑ Recent advances in multidisciplinary applied physics By A. Méndez-Vilas. Page 65.
  4. ↑ R. Barra, D. Llanwyn Jones, CJ Rodger (2000): ELF and VLF radio waves in the Journal of Atmospheric and Solar-Terrestrial Physics 62 , Elsevier