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The global electromagnetic resonance phenomenon is named after physicist Winfried Otto Schumann who predicted it mathematically in 1952. Schumann resonances are the principal background in the part of the electromagnetic spectrum [2] from 3 Hz through 60 Hz [3] and appear as distinct peaks at extremely low frequencies around 7.83 Hz (fundamental), 14.3, 20.8, 27.3, and 33.8 Hz.
The fundamental Schumann resonance is at approximately 7.83 Hz, the frequency at which the wavelength equals the circumference of the Earth, and higher harmonics occur at 14.1, 20.3, 26.4, and 32.4 Hz, etc. Lightning strikes excite these resonances, causing the Earth–ionosphere cavity to "ring" like a bell, resulting in a peak in the noise ...
The Schumann resonances are a set of spectrum peaks in the extremely low frequency (ELF) portion of the Earth's electromagnetic field spectrum. Schumann resonance is due to the space between the surface of the Earth and the conductive ionosphere acting as a waveguide. The limited dimensions of the earth cause this waveguide to act as a resonant ...
The Earth–ionosphere waveguide [1] is the phenomenon in which certain radio waves can propagate in the space between the ground and the boundary of the ionosphere. Because the ionosphere contains charged particles, it can behave as a conductor. The earth operates as a ground plane, and the resulting cavity behaves as a large waveguide.
Use of NASA logos, insignia and emblems is restricted per U.S. law 14 CFR 1221.; The NASA website hosts a large number of images from the Soviet/Russian space agency, and other non-American space agencies.
Measurements of Schumann resonances at only a few stations around the world can monitor the global lightning activity fairly well. [14] One can apply the dispersive property of the Earth–ionosphere waveguide by measuring the group velocity of a sferic signal at different frequencies together with its direction of arrival. The group time delay ...
In the case of opposite propagation direction the groups travel at a much larger speed, which is now 2π(f 1 + f 2)/(k 1 − k 2) with k 1 and k 2 the wave numbers of the interacting water waves. Wave groups generated by waves with same directions. The blue curve is the sum of the red and black. In the animation, watch the crests with the red ...
Natural frequency, measured in terms of eigenfrequency, is the rate at which an oscillatory system tends to oscillate in the absence of disturbance. A foundational example pertains to simple harmonic oscillators, such as an idealized spring with no energy loss wherein the system exhibits constant-amplitude oscillations with a constant frequency.