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# Synopsis of the historical development of Schumann resonances

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## Abstract

The life and work of Winfried Otto Schumann and the historical development of the main ideas leading to the hypothesis of Earth-ionosphere cavity electromagnetic oscillations are reviewed. The so-called Schumann resonances are a set of frequencies of electromagnetic waves in the natural cavity formed by a planet's (moon's) surface and its ionosphere, in the extremely low frequency (ELF) range, caused by natural electrical activity of the planet (moon) and/or its atmospheric environment. Additionally, the reception of his work by the contemporary scientific community as well as the experimental evidence for the postulated ELF resonance oscillations is described.

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... Winfried Otto Schumann, a professor at the Technische Hochschule München, rightfully gets most of the credit for predicting Schumann Resonances. However, Schumann resonance history is an interesting story [26]. The idea of natural global electromagnetic resonances goes back to George F. Fitzgerald in 1893 and Nikola Tesla in 1905 [26,27]. ...
... However, Schumann resonance history is an interesting story [26]. The idea of natural global electromagnetic resonances goes back to George F. Fitzgerald in 1893 and Nikola Tesla in 1905 [26,27]. The formula (23) for resonance frequencies of a spherical condenser was first obtained by Joseph Larmor already in 1894 [26]. ...
... The idea of natural global electromagnetic resonances goes back to George F. Fitzgerald in 1893 and Nikola Tesla in 1905 [26,27]. The formula (23) for resonance frequencies of a spherical condenser was first obtained by Joseph Larmor already in 1894 [26]. ...
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It is believed that an asteroid/comet impact 65 million years ago ended the dinosaur era. The researchers named the corresponding impact crater Chicxulub, the Mayan word roughly translated as “the dragon's tail.” We estimate the expected magnitudes of the Schumann resonance fields immediately after the Chicxulub impact and show that they exceed their present-day values by about 5×104 times. Long-term distortion of the Schumann resonance parameters is also expected due to the environmental impact of the Chicxulub event. If Schumann resonances play a regulatory biological role, as some studies indicate, it is possible that the excitation and distortion of Schumann resonances after the asteroid/comet impact was a possible stress factor, which, among other stress factors associated with the impact, contributed to the demise of dinosaurs.
... Winfried Otto Schumann, a professor at the Technische Hochschule München, rightfully gets most of the credit for predicting Schumann Resonances. However, Schumann resonance history is an interesting story [22]. The idea of natural global electromagnetic resonances goes back to George F. Fitzgerald in 1893 and Nikola Tesla in 1905 [22,23]. ...
... However, Schumann resonance history is an interesting story [22]. The idea of natural global electromagnetic resonances goes back to George F. Fitzgerald in 1893 and Nikola Tesla in 1905 [22,23]. The formula (23) for resonance frequences of a spherical condenser was first obtained by Joseph Larmor already in 1894 [22]. ...
... The idea of natural global electromagnetic resonances goes back to George F. Fitzgerald in 1893 and Nikola Tesla in 1905 [22,23]. The formula (23) for resonance frequences of a spherical condenser was first obtained by Joseph Larmor already in 1894 [22]. ...
Preprint
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We estimate the expected magnitudes of the Schumann resonance fields immediately after the Chicxulub impact and show that they exceed their present-day values by about $5\times 10^4$ times. Long-term distortion of the Schumann resonance parameters is also expected due to the enviromental impact of the Chicxulub event. If Schumann resonances play a regulatory biological role, as some studies indicate, it is possible that the excitation and distortion of Schumann resonances as a result of the asteroid/comet impact was a possible stress factor, which, among other stress factors associated with the impact, contributed to the demise of dinosaurs.
... giving 10.6, 18.4, and 25.9 Hz for l ¼ 1, 2, 3, respectively. These are the so-called Schumann frequencies [18], though Schumann was not the first to obtain this result [19,20]. These extremely-low frequency (ELF) waves were measured by Balser and Wagner in 1960, and the frequencies of the first three modes were found to be 7.8, 14.1, and 20.3 Hz [21], i.e., ∼20% lower than those predicted by Eq. (1). ...
... This approach is advantageous since the electromagnetic fields satisfy the same boundary conditions as in the massless case [16]. Using Eq. (20), from Eqs. (6d) and (3) ...
Article
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The photon is the paradigm for a massless particle, and current experimental tests set severe upper bounds on its mass. Probing such a small mass, or equivalently large Compton wavelength, is challenging at laboratory scales, but planetary or astrophysical phenomena may potentially reach much better sensitivities. In this work, we consider the effect of a finite photon mass on Schumann resonances in the Earth-ionosphere cavity, since the transverse magnetic modes circulating Earth have eigenfrequencies of order O(10 Hz) that could be sensitive to mγ≈10−14 eV/c2. In particular, we update the limit from Kroll [Phys. Rev. Lett. 27, 340 (1971)], mγ≤2.4×10−13 eV/c2, by considering realistic conductivity profiles for the atmosphere. We find the conservative upper bound mγ≤2.5×10−14 eV/c2, a factor 9.6 more strict than Kroll’s earlier projection.
... Given system processes this signal in the form of a certain algorithm (8), through the amplifying equipment (7), for some time. Then, the received signal is sent to the modulator (9), which is irradiating the object with ultra short pulses (about 1 NS) of ultra-wideband (bandwidth of several gigahertz) electromagnetic radiation of the microwave range through the emitter (10). Emitter will generate a stimulating effect (11) [10-12 - figure (4)]. ...
... The x-ray emitter (5) is controlled by a device (6). The stimulating effect (7) is carried out by means of an electromagnetic field radiated by a broadband emitter (8) [10-12 - figure (4)], whose operation is controlled by a modulator (9). Modulator puts into the radiation an information component obtained according to the scheme described earlier. ...
Article
The principles discussed in this article are similar to the processes that occur every second in nature. They are the basis of the bionic model under consideration in the framework of nano -, bio -, info -, and cognoconvergence (nbic-convergence). This model is similar to the processes of quantum teleportation that occur in natural biogeocenoses and ecosystems. The article also discusses ways to "preserve" entangled states in crystals as optically active nonlinear media. The following is a method of hypothetical physiotherapy for modeling persistent remissions of multiple sclerosis due to the remyelination process. This method creates some forced conditions for the execution of the macroscopic quantum teleportation protocol. The considered hypothetical model can also be used for reconvalescence of a wide range of nosological forms.
... In its simplest form, if both Earth surface (radius a) and ionosphere (height h) are considered as being electric conductive, a cavity is formed in the shape of two concentric spheres. Already in 1894, Larmor [1] arrived at the same equation Schumann derived later in 1952 [2] for the resonating modes f n , with the condition that the ionosphere height h is much smaller than the Earth radius a f n = c 2πa n (n + 1) ...
... Proper detection of these Schumann resonances is difficult because resonant antennas tend to be too large and also due to the 60/50 Hz power line interferences, whose amplitudes are usually much larger than that of the picked up signal. Their effective detection was delayed until the end of the 1950s because only analog electronic filtering was then available; later on, modern spectral techniques helped filter out the desired signals from the ambient noise [2]. Experimental confirmation of the Schumann resonances (the first five modes) took place in 1960 [10]. ...
Article
The electromagnetic simulation of the Earth eigenfrequencies is covered, the so-called Schumann resonances. Comparisons to analytical and also measured results are presented, validating the approach. Similar numerical evaluations performed in time domain (Finite Difference Time Domain) and Frequency Domain (Finite Element Method) are also used for comparisons. The eigenmode resonances hereby computed do not need a source of excitation, unlike time-domain codes. A simple Earth model is evaluated (two concentric lossless metallic spheres), as well as one model with a 10-layer atmosphere finite conductivity profile, and also an oblate spheroid geometry. To the knowledge of the author, this is the first reported electromagnetic simulation of the Earth Schumman Eigenomodes, considering it a closed structure without need for excitation. The eigenmode analysis allows a simple and effective resonance frequency of not only the Earth but also other planets. Comparisons to available experimental data prove the effectiveness of the analysis.
... In fact (1), as a formula describing oscillations in a spherical condenser with the small separation distance between spheres, was obtained already in 1894 by Joseph Larmor [20]. In general, Schumann resonances history is an interesting story including such names as George Fitzgerald and Nikola Tesla [20]. ...
... In fact (1), as a formula describing oscillations in a spherical condenser with the small separation distance between spheres, was obtained already in 1894 by Joseph Larmor [20]. In general, Schumann resonances history is an interesting story including such names as George Fitzgerald and Nikola Tesla [20]. ...
Article
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Recently it was claimed that the LIGO residual noise at the time of the GW150914 gravitational-wave detection event contains some unexplained correlated noise. At that the noise correlations are maximized at the same time-delay as the signal correlations in two LIGO detectors. We argue that the Schumann resonance transients excited by strong lightnings and Q-bursts in Africa will have just this time lag of about 7~ms. Therefore if the correlated noise related to the Schumann resonance transients is indeed present in the LIGO data, its "African part" will show just the proper time-delay and its coincidence with the gravitational-wave time delay is only a coincidence.
... The Schumann Resonances (SR) are global electromagnetic resonances excited within the Earth-ionosphere waveguide, primarily by lightning discharges. These resonances occur in the extremely low frequency (ELF) range, with resonant frequencies around 8Hz, 14 Hz, 20 Hz, 26 Hz, etc.The history of the Schumann Resonances (SR) is an interesting story[1]. While Schumann[2]gets most of the credit for the first prediction of the existence of the SR, the idea of natural global electromagnetic resonances were first presented by George F. Fitzgerald in 1893, and then again by Nikola Tesla in 1905[3]. ...
... Today we know that we need 5–10 min of data to detect the SR clearly in the spectrum. For further insight into the history of the SR, the reader is pointed to this excellent review[1]. Following Schuman's landmark paper in 1952, there was an increasing interest in SR in a wide variety of fields. ...
Article
Lightning produces electromagnetic fields and waves in all frequency ranges. In the extremely low frequency (ELF) range below 100 Hz, the global Schumann Resonances (SR) is excited at frequencies of 8 Hz, 14 Hz, 20 Hz, etc. This review is aimed at the reader generally unfamiliar with the Schumann Resonances. First some historical context to SR research is given, followed by some theoretical background and examples of the extensive use of Schumann resonances in a variety of lightning-related studies in recent years, ranging from estimates of the spatial and temporal variations in global lighting activity, connections to global climate change, transient luminous events and extraterrestrial lightning. Both theoretical and experimental results of the global resonance phenomenon are presented. It is our hope that this review will increase the interest in SR among researchers previously unfamiliar with this phenomenon.
... These resonances occur in the extremely low frequency (ELF) range, with resonant frequencies around 8 Hz, 14 Hz, 20 Hz, 26 Hz, etc. The history of the Schumann Resonances (SR) is an interesting story [1]. While Schumann [2] gets most of the credit for the first prediction of the existence of the SR, the idea of natural global electromagnetic resonances were first presented by George F. Fitzgerald in 1893, and then again by Nikola Tesla in 1905 [3]. ...
... Today we know that we need 5-10 min of data to detect the SR clearly in the spectrum. For further insight into the history of the SR, the reader is pointed to this excellent review [1]. ...
Article
Full-text available
Lightning produces electromagnetic fields and waves in all frequency ranges. In the extremely low frequency (ELF) range below 100 Hz, the global Schumann Resonances (SR) are excited at frequencies of 8 Hz, 14 Hz, 20 Hz, etc. This review is aimed at the reader generally unfamiliar with the Schumann Resonances. First some historical context to SR research is given, followed by some theoretical background and examples of the extensive use of Schumann resonances in a variety of lightning-related studies in recent years, ranging from estimates of the spatial and temporal variations in global lighting activity, connections to global climate change, transient luminous events and extraterrestrial lightning. Both theoretical and experimental results of the global resonance phenomenon are presented. It is our hope that this review will increase the interest in SR among researchers previously unfamiliar with this phenomenon.
... They were first predicted by Schumann [9], and measured by Balser and Wagner [10]. An excellent historical review of their study can be found in [11]. Interest in them has grown significantly with the work of Williams [12], who related the SR to the global temperature of Earth. ...
... The TM r modes can be divided into two different kinds. One consists of modes with half-wavelengths related to the Earth's perimeter; these are known as Schumann resonances [30,11]. The other kind of TM r and all the TE r modes have half-wavelengths proportional to the distance between the ground and the ionosphere; these are known as transverse resonances [31][32][33]. ...
... On Titan, the absence of a significant natural magnetic field prevents the propagation of whistler modes, only allowing the existence of atmospherics, electromagnetic modes which remain confined between the ground and lower layers of the ionosphere. Schumann resonance fre-quencies are a very special case of atmospherics (Sentman, 1995;Besser, 2007). These resonances are the lowest resonant frequencies in the electromagnetic ground-ionosphere cavity, being related to TM r modes with horizontal components of the electric field two-orders of magnitude lower than the radial component (Sentman, 1990). ...
... If the atmosphere between the two conductive layers is not excessively dissipative, global lightning activity excites the resonant frequencies for the electromagnetic field in the cavity. The frequencies corresponding to the lower order modes are known as Schumann's resonances (Sentman, 1995;Besser, 2007). For the Earth, these resonance frequencies were first predicted by Schumann (1952), and later detected by Balser and Wagner (1960). ...
Article
A procedure is shown for extracting weak resonances from the responses of electromagnetic systems excited by electric discharges. The procedure, based on analysis of the late-time system response, is first checked using an analytical function and later with the data for the electric field generated by the computational simulation of Titan's atmosphere using the Transmission Line Matrix (TLM) method. Finally, the low frequency spectrum of the natural electric field in Titan's atmosphere sent by the mutual impedance sensor (MIP) included in the Huygens probe is analyzed employing this technique. The MIP sensor was initially designed to measure the horizontal component of the electric field during a quiet descent. Fortunately, the swinging that occurred during the descent allowed the MIP to measure the radial component of the electric field mixed with the horizontal one. Application of the late-time analysis technique shown in this paper confirms the signature of lightning reported by preliminary data observations, bringing out the expected eigenfrequencies of the Titan-ionosphere electromagnetic cavity, known as Schumann resonances. These resonances are the resonant frequencies of the lower TMr (transverse magnetic to r) modes, which are quasi-transverse electromagnetic modes because they present vertical or radial components of the electric field two orders of magnitude higher than the associated horizontal, azimuthal and zenithal, components. The sequence of Schumann resonances is unique for each celestial body with an ionosphere, since these resonances are fully determined by the dimensions of the planet or satellite and the corresponding atmospheric conductivity profile. Detecting these frequencies in an atmosphere is clear proof of electrical activity, since it implies the existence of an electromagnetic-energy source, which is essential to create and maintain them.
... Here a few historical remarks on this transformation named after Watson and Sommerfeld and its application seems to be in order to show what is really new in this paper. We refer to Besser's review [13] and to reviews and work cited by this author for more details. The transformation just mentioned was introduced at the beginning of the 20-th century in investigations on the propagation of long radio waves around the earth. ...
... [16]. Watson's formula was later used by Schumann to treat the resonances of the electromagnetic oscillations in the earth-ionosphere cavity now bearing his name, see [13]. The representation of the electromagnetic or optical field in the exterior of a sphere or an infinite cylinder obtained by a Sommerfeld Watson transformation as described in the preceding lines has been and is still used extensively, see e.g. ...
Article
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This paper deals with the three-dimensional potential equation in cylindrical coordinates and its Green’s function for a geometry close to a typical Time Projection Chamber field-cage, namely a coaxial cavity. The derivations of three different representations of the Green’s function are described in detail. Each one is a sum over two of the three labels of the eigenfunctions of the homogeneous boundary value problem; the coefficients correspond to one-dimensional Green’s functions in the third variable, which are found by the method of particular integrals. The third representation is an innovative one using modified Bessel function of purely imaginary order, which can also be derived by a Sommerfeld-Watson transformation. In combination, these three representations allow fast converging calculations of the potential and the electric field for nearly any position of the point charge and therefore for any desired space charge configuration within the cavity.
... These are the so-called Schumann frequencies[15], though W.O. Schumann was not the first to obtain this result[16,17]. ...
Preprint
The photon is the paradigm for a massless particle and current experimental tests set severe upper bounds on its mass. Probing such a small mass, or equivalently large Compton wavelength, is challenging at laboratory scales, but planetary or astrophysical phenomena may potentially reach much better sensitivities. In this work we consider the effect of a finite photon mass on Schumann resonances in the Earth-ionosphere cavity, since the TM modes circulating Earth have eigen-frequencies of order $\mathcal{O} (10 \, {\rm Hz})$ that could be sensitive to $m_\gamma \approx 10^{-14} \, {\rm eV/c}^2$. In particular, we update the limit from Kroll [Phys. Rev. Lett. 27, 340 (1971)], $m_\gamma \leq 2.4 \times 10^{-13} \, {\rm eV/c}^2$, by considering realistic conductivity profiles for the atmosphere. We find the conservative upper bound $m_\gamma \leq 2.5 \times 10^{-14} \, {\rm eV/c}^2$, a factor 9.6 more strict than Kroll's earlier projection.
... SRs were predicted in 1952, and first detected by Balser and Wagner (1962). A historical review on the progress of SR studies can be found in (Besser 2007). ...
Article
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In this work, we present to the scientific community the measurements taken during four years, from March 2013 to February 2017 inclusive, by the Extremely Low Frequency Sierra Nevada station, Spain, together with the data processing programs developed in Python (version 3.8) to extract the Schumann resonance (SR) parameters (i.e., amplitudes, resonant frequencies, resonance widths) in 10 min time periods from these records. The measurements correspond to the voltage induced by the atmospheric electromagnetic field at the north-south and east-west oriented magnetometers of the station. The process comprises four stages. The spectrum, calibrated in the frequency band ranging from 6 Hz to 25 Hz, is obtained at the first stage using the Welch method with Hann windows. The second step eliminates the anthropogenic noise generated by different undesired sources. Next, a non-linear fit of the measured spectrum combining Lorentzian functions together with a linear term is carried out in order to identify the presence of SRs and quantitatively characterize them. This third step is carried out using the Python package Lmfit, which implements the Levenberg-Marquad algorithm. Finally, a compact and easy-to-read output is generated at the fourth stage, using the power of the Numpy arrays and the npz format. In addition, four Jupyter notebooks with the description of the code and the possibility of their use in interactive mode are presented as supplementary material with this paper.
... However, the basic living environment is only the Earth's water, which has a necessary deuterium concentration. We have emphasized this fact above and would like to draw your attention once again to the uniqueness of these chemical, biological, and physical processes and, especially, to the non-occasional coincidence between the frequencies of Earth's and human brain oscillations, i.e., so-called Schumann frequencies [13]. This is the most important and principal biological life fact, which requires more profound studies. ...
... [44] Fourth, there is a relationship between the biological mechanisms of the human being with Schumann waves and a geomagnetic field [45]. This phenomenon was named in honour of Winfried Otto Schumann [46], who mathematically predicted its existence in 1952, despite being detected for the first time by Nikola Tesla [47]. The first spectral representation of this phenomenon was conducted by Balser and Wagner in 1960 [48]. ...
Article
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Since the origin of the Modern Movement, there has been a basic commitment to improving housing conditions and the well-being of occupants, especially given the prediction that 2/3 of humanity will reside in cities by 2050. Moreover, a compact model of the city with tall buildings and urban densification at this scale will be generated. Continuous constructive and technological advances have developed solid foundations on safety, energy efficiency, habitability, and sustainability in housing design. However, studies on improving the quality of life in these areas continue to be a challenge for architects and engineers. This paper seeks to contribute health-related information to the study of residential design, specifically the influence of the geomagnetic field on its occupants. After compiling information on the effects of geomagnetic fields from different medical studies over 23 years, a case study of a 16-story high-rise building is presented, with the goal of proposing architectural design recommendations for long-term occupation in the same place. The purpose of the present work is three-fold: first, to characterize the geomagnetic field variability of buildings; second, to identify the causes and possible related mechanisms; and third, to define architectural criteria on the arrangement of uses and constructive elements for housing.
... The signature of SRs is present not only in ELF station measurements specifically designed for tracking the electromagnetic activity in the atmosphere but also in registers initially intended for other applications, such as the case of magnetoteluric records, devised for the study of the structure and composition of the Earth's subsurface , for instance. The work by Hayakawa [2002, 2014] provides a full and comprehensive description of the fundamentals of SRs, and a significant historical review was carried out by Besser [2007]. Since an important part of the Earth-ionosphere resonator is the ionosphere itself, the variations of the ionosphere conductivity profile, which is associated with solar activity, have a strong influence on SR parameters. ...
Article
The effects of solar storms occurring during the days 17 to 19 March 2013 and 2015, St. Patrick's Day intervals, on Schumann Resonances (SRs) have been studied. To do this, the experimental data recorded by the Juan Antonio Morente Extremely Low Frequency (ELF) station located at Sierra Nevada, Spain, have been processed in order to obtain hourly averaged information on the first three resonance modes. Results are compared with monthly averages of the SR data for each hour to detect deviations from the regular behavior. Evidence of significant changes in the peak amplitudes and frequencies of the SRs have been identified in the station's measurements and related to the Coronal Mass Ejection impact in the magnetosphere, detected by in-situ plasma measurements onboard spacecraft in the solar wind. However, the complicated nature of the Schumann resonances, dependent on multiple variables and subject to multiple unavoidable interferences (e.g., lightning or human radio sources), in conjunction with the complex magnetosphere-ionosphere-atmosphere coupling processes, makes it difficult to conclude that the observed deviations are exclusively due to the solar events mentioned. Results extracted from only two solar events cannot be considered as conclusive, and therefore, independent comparison with results reported by other research would seem advisable in future works on this subject.
... The Schumann Resonances (SR) were first measured by Balser and Wagner [1960], and their values are roughly 8, 14, and 20 Hz for the first three modes. A great historical review of the beginnings of this topic can be found in Besser [2007]. The difference between the analytical prediction and the measurements is explained by the losses in the dielectric, not accounted for in the analytical model. ...
Article
Full-text available
Schumann resonances can be found in planetary atmospheres, inside the cavity formed by the conducting surface of the planet and the lower ionosphere. They are a powerful tool to investigate both the electric processes that occur in the atmosphere and the characteristics of the surface and the lower ionosphere. Results from a full 3-D model of the Earth-ionosphere electromagnetic cavity based on the Transmission-Line Modeling (TLM) method are presented. A Cartesian scheme with homogeneous cell size of 10 km is used to minimize numerical dispersion present in spherical schemes. Time and frequency domain results have been obtained to study the resonance phenomenon. The effect of conductivity on the Schumann resonances in the cavity is investigated by means of numerical simulations, studying the transition from resonant to nonresonant response and setting the conductivity limit for the resonances to develop inside the cavity. It is found that the transition from resonant to nonresonant behavior occurs for conductivity values above roughly 10-9 S/m. For large losses in the cavity, the resonances are damped, but, in addition, the peak frequencies change according to the local distance to the source and with the particular electromagnetic field component. These spatial variations present steep variations around each mode's nodal position, covering distances around 1/4 of the mode wavelength, the higher modes being more sensitive to this effect than the lower ones. The dependence of the measured frequency on the distance to the source and particular component of the electric field offers information on the source generating these resonances.
... Because proton density is related to the passing of certain frequencies, the frequency of radio waves that penetrates into space and does not deflect back to earth can be used to estimate the proton density of at a given altitude. In the 1950s Winfried Otto Schumann predicted that the boundaries formed by the earth and the ionosphere could function as a waveguide for resonant electromagnetic frequencies (Besser, 2007). Resonance can be expressed as a property of all matter such that its physical characteristics produce a structure that allows the object to oscillate at particular frequencies. ...
Thesis
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There exists a space between the ionosphere and the surface of the earth within which electromagnetic standing waves, generated by lightning strikes, can resonate around the earth; these standing waves are known collectively as the Schumann resonances. In the late 1960s König and Ankermuller already reported striking similarities between these electromagnetic signals and those recorded from the electroencephalograms (EEG) of the human brain; both signals exhibit similar characteristics in terms of frequency and electric and magnetic field intensity. The analyses reported here demonstrate that 1) microscopic (brain) and macroscopic (earth) representations of natural electromagnetic fields are conserved spatially, 2) that electric fields recorded from human brains exhibit strong correlation with the strength of the these parameters and 3) that the human brain periodically synchronizes with signals generated within the earth-ionosphere waveguide at frequencies characteristic of the Schumann resonance for periods of about 300 msec. These findings recapitulate 17th century ideas of harmony amongst the cerebral and planetary spheres and may provide the means necessary to quantitatively investigate concepts of early 20th century psychology.
... Subsequent modes are found at 14, 21, 28, and 32 Hz, approximately. A very good historical review of SRs can be found in Besser [2007]. It is worth noting that the study of the frequency band between 0.01 and 20 Hz is of special interest in order to understand the energy transfer mechanisms between the atmosphere and the ionosphere [Bösinger et al., 2002;Semenova and Yahnin, 2008] and between the magnetosphere and the ionosphere (spectral resonances structures) [Prikner et al., 2004]. ...
Article
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A new permanent ELF measurement station has been deployed in Sierra Nevada, Spain. It is composed of two magnetometers, oriented NS and EW, respectively. At 10 Hz, their sensitivity is 19μzV/pT and the Signal to Noise Ratio (SNR) is 28 dB for a time-varying signal of 1 pT, the expected field amplitude in Sierra Nevada. The station operates for frequencies below 24 Hz. The magnetometers, together with their corresponding electronics, have been specifically designed to achieve such an SNR for small signals. They are based on high-resolution search coils with ferromagnetic core and 106 turns, operating in limited geometry configuration. Different system noise sources are considered and a study of the SNR is also included. Finally, some initial Schumann resonance measurements are presented in order to validate the performance of the measurement station, including one hour length spectra, daily variations of resonance amplitudes and frequencies for the different seasons, and a three day spectrogram.
... The largest spectral density of the atmospheric electrical discharge is concentrated in the VLF band ($few kHz), though comparable spectral power is contained in the lower ELF-ULF bands (from fractions of Hz to few tens of Hz). In the ELF band, the global Earth-ionosphere cavity Schumann resonances (SR) with the fundamental mode at$ 7.8 Hz and multiple harmonics are permanently activated by the world thunderstorm centers (Nickolaenko and Hayakawa, 2002;Besser, 2007). ...
... To address this, a method was needed to identify and probe lightning strokes that may occur at long range from a sensor. Fortunately, lightning is a very powerful radiator of electromagnetic energy from VLF and LF [Rakov and Uman 2003, p. 6] all the way down to the Schumann resonance band of a few Hz [Besser, 2007], and it has been well known for decades that electromagnetic waves at these low frequencies can travel extremely long distances while guided by the Earthionosphere waveguide [Barr et al., 2000]. The typical sensorto-sprite distances of hundreds to thousands of km makes VLF and lower-frequency measurements an ideal tool for studying TLE-producing lightning. ...
Article
Extremely low frequency (ELF) and very low frequency (VLF) observations have formed the cornerstone of measurement and interpretation of effects of lightning discharges on the overlying upper atmospheric regions, as well as near-Earth space. ELF (0.3-3 kHz) and VLF (3-30 kHz) wave energy released by lightning discharges is often the agent of modification of the lower ionospheric medium that results in the conductivity changes and the excitation of optical emissions that constitute transient luminous events (TLEs). In addition, the resultant ionospheric changes are best (and often uniquely) observable as perturbations of subionospherically propagating VLF signals. In fact, some of the earliest evidence for direct disturbances of the lower ionosphere in association with lightning discharges was obtained in the course of the study of such VLF perturbations. Measurements of the detailed ELF and VLF waveforms of parent lightning discharges that produce TLEs and terrestrial gamma ray flashes (TGFs) have also been very fruitful, often revealing properties of such discharges that maximize ionospheric effects, such as generation of intense electromagnetic pulses (EMPs) or removal of large quantities of charge. In this paper, we provide a review of the development of ELF and VLF measurements, both from a historical point of view and from the point of view of their relationship to optical and other observations of ionospheric effects of lightning discharges.
... [2] The propagation of extremely low frequency (ELF) electromagnetic waves in the cavity bounded by two, highly conductive, concentric, spherical shells, like that approximated by the surface and the ionosphere of Earth, was first studied theoretically by Schumann [1952]; this phenomenon was first observed by Balser and Wagner [1960]. These and other early works have been reviewed by Besser [2007]. When electromagnetic sources pump energy in a spherical cavity, a resonant state develops whenever the average cavity perimeter approaches an integral multiple of the signal wavelength. ...
Article
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The propagation of extremely low frequency (ELF) waves in the Earth surface-ionosphere cavity and the properties of the related Schumann resonances have been extensively studied in order to explain their relation with atmospheric electric phenomena. A similar approach can be used to understand the electric environment of Venus and, more importantly, search for the evidence of possible atmospheric lightning activity, which remains a controversial issue. We revisit the available models for ELF propagation in the cavity of Venus, recapitulate the similarities and differences with other planets, and present a full wave propagation finite element model with improved parameterization. The new model introduces corrections for refraction phenomena in the atmosphere; it takes into account the day-night asymmetry of the cavity and calculates the resulting eigenfrequency line splitting. The analytical and numerical approaches are validated against the very low frequency electric field data collected by Venera 11 and 12 during their descents through the atmosphere of Venus. Instrumentation suitable for the measurement of ELF waves in planetary atmospheres is briefly addressed.
... The TM r modes can be divided into two different kinds. One is made up of modes with half wavelengths related to the Earth's diameter and these are known as Schumann resonances [Sentman, 1995;Besser, 2007]. The other kind of TM r and all the TE r modes have half wavelengths proportional to the distance between the ground and the ionosphere and these are called transverse resonances [Poeverlein, 1961;Bliokh et al., 1977;Nikolaenko and Rabinovich, 1982]. ...
Article
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A numerical simulation of Titan's electromagnetic cavity in the VLF band is carried out using the Transmission Line Matrix (TLM) method, with the aim of assessing the VLF electric field spectra sent by the Huygens probe. In an Earth-like model, successive peaks would be expected in the spectra, associated with multiple reflections of the electromagnetic wave on the external surfaces of Titan's electromagnetic cavity, formed by the ionosphere and a conductive ground or underground surface. However, owing to high losses conferred by the electrical conductivity to Titan's atmosphere, the direct numerical and experimental spectra are decreasing functions of the frequency without resonances or other special forms. The weak atmospheric resonances are extracted from the data measured by the Huygens's sensors after a procedure based on analysis of the late time response is applied to the experimental spectra. The new late time spectra present the appearance expected, with successive peaks and a mean between adjacent resonances of 0.67 kHz, in agreement with the late time TLM results when the Borucki et al. (2006) conductivity profile with aerosols is introduced in the numerical model. This gap in frequency between successive peaks gives an effective optical distance between the ground and the conductive ionosphere of approximately 220 km, considerably higher than the terrestrial one where this distance is around 75 km.
... However, at around 40–50 km of height from the surface, the lower ionosphere becomes increasingly conductive for waves below the MHz range, at a rate of approximately one order of magnitude for each 10 km [Tran and Polk, 1979]. This structure forms an electromagnetic cavity with its own resonant modes in the extremely low frequency (ELF) and ultra low frequency (ULF) ranges [Schumann, 1952; Besser, 2007]. This cavity can accommodate two kinds of standing waves: the transverse electric (TE r ) and the transverse magnetic (TM r ) to the radial direction modes. ...
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Eight independent magnetotelluric (MT) campaigns, carried out in the western Mediterranean area and Antarctica, have been analyzed with the aim of extracting information from Schumann resonances (SR). The advantages and drawbacks of MT data with respect to single-purpose fixed stations for SR research are evaluated. Two different methods of signal processing have been employed: spectral analysis through the fast Fourier transform (FFT) and Rescaled Range analysis (R/S), calculating the Hurst exponents. The first permitted a study of the source contributions, the effects caused by local changes in the observation area, interseasonal behavior, and the relations between electric and magnetic horizontal fields. The average central frequencies obtained for the first three resonances are 7.8, 14, and 20.5 Hz respectively, but there are fluctuations in them. These variations seem to respond to the characteristics of the principal active storms that generate the resonances. These frequency shifts are stronger for the second and third resonances. Owing to the broadband registering of MT, the second method of signal processing could be applied to the low noise signals from Antarctica with high resolution, revealing the persistent nature of SR. A numerical simulation indicates a way for inferring lightning rates from R/S analysis.
... Following the notation given in [7], with the script n and m as indices for the associated Legendre functions or spherical harmonics and with the script p indicating the successive zeroes of the spherical Bessel function of order n in the TE r modes, or its derivative for TM r modes, all the TE r mnp modes and the TM r mnp with p = 1 are called transverse resonances8910; they fall almost entirely within the VLF band, with half-wavelengths proportional to the distance between the ground and the ionosphere, and are local phenomena because their energy remains concentrated around the excitation source [11, 12]. However, the TM r mn1 modes, known as Schumann resonances [13, 14], are modes globally coupled with the Earth-ionosphere cavity that should be detected anywhere on Earth and their resonant frequencies are in the ELF band. The propagation of ELF-VLF radio waves in the terrestrial atmosphere has been widely studied, due to its importance in communication and navigation systems. ...
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The sequence of Schumann resonances is unique for each celestial body with an ionosphere, since these resonances are determined by the dimensions of the planet/satellite and the corresponding atmospheric conductivity profile. Detecting these frequencies in an atmosphere is a clear proof of electrical activity, since it implies the existence of an electromagnetic energy source, which is essential for their creation and maintenance. In this paper, an analysis procedure for extracting weak resonances from the responses of electromagnetic systems excited by electric discharges is shown. The procedure, based on analysis of the late-time system response, is first checked using an analytical function and later applied to the vertical electric field generated by the computational simulation of Earth's atmosphere using the TLM (Transmission Line Matrix) method in order to extract the weak Schumann resonances contained in this electric field component.
... The surface and ionosphere of the Earth form a cavity that, when excited with a broadband electromagnetic spectrum, can develop resonant states for which the average equatorial circumference is approximately equal to an integral number of wavelengths of the electromagnetic waves trapped in the resonator. This phenomenon was studied first theoretically by Schumann (1952, for an historical perspective, see Besser 2007) and later observed by Balser and Wagner (1960). For Schumann resonances to exist a broad initial electromagnetic source spectrum is required. ...
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The propagation of extremely low frequency (ELF, 3 Hz to 3 kHz) radio waves and resonant phenomena in the spherical Earth-ionosphere cavity has been studied for almost fifty years. When such a cavity is excited by naturally occurring broadband electromagnetic radiation, resonances can develop if the equatorial circumference is approximately equal to an integral number of wavelengths of the propagating electromagnetic waves; these are termed Schumann resonances. They provide information not only about thunderstorm and lightning activity on the Earth, and their relation to climate, but also on the properties of the low ionosphere. Similar investigations can be performed for any other planet or satellite, provided that it has an ionosphere.
... Contemporary knowledge is summarized in an excellent monograph by Nickolaenko and Hayakawa (2002). The comprehensive synopsis of SR phenomenon history can be found in Besser (2007). ...
Article
Superimposed on the continuous Schumann resonance (SR) background in the extremely low frequency (ELF) band, transient signals (e.g. bursts) can be observed, which originate from intense lightning discharges occurring at different locations on the globe. From the many transients that were observed at the Astronomical and Geophysical Observatory (AGO) of Comenius University near Modra, western Slovakia, in the vertical electric field component mainly during May and June of 2006, a peculiar group of events could be recognized. According to the waveform analysis, these peculiar events in most cases consist of two overlapping transients with a characteristic time difference of 0.13–0.15 s between the onsets. On the other hand, the spectrum of these peculiar transients showed discernible SR peaks for higher modes as well (n>7). The same events could be found in the records of the Széchenyi István Geophysical Observatory of the Geodetic and Geophysical Research Institute of the Hungarian Academy of Sciences near Nagycenk, Hungary (NCK). The natural origin of the peculiar events was verified from the NCK data and the source location was determined from the second transient. The results suggest that the two consecutive transients originated in the same thunderstorm. Furthermore, the phase spectrum analysis indicates that the sources have coherently excited the Earth-ionosphere cavity. These findings seem to support the idea that electromagnetic waves orbiting the Earth might trigger lightning discharges. The possibility that electromagnetic waves may trigger discharges was first considered by Nikola Tesla.
... In addition to the discovery of that layer, an intriguing signal appearing in the ELF data as a quasi-monochromatic line, a few Hz wide, centered at around 36 Hz and present almost continuously throughout the descent, has been investigated by Simões et al. (2007) and Bé ghin et al. (2007). Among several possibilities of instrumental or natural origin, these authors concluded that the observed signal might have been the second eigenmode of a Schumann-like resonance in Titan's atmospheric cavity, with a noticeable specificity with respect to the well-known Schumann resonance on Earth (Schumann, 1952; for a historical review see Besser, 2007). ...
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After a preliminary analysis of the low-frequency data collected with the electric antenna of the Permittivity, Wave and Altimetry (PWA) experiment onboard the Huygens Probe that landed on Titan on 14 January, 2005, it was anticipated in a previous article [Béghin et al., 2007. A Schumann-like resonance on Titan driven by Saturn's magnetosphere possibly revealed by the Huygens Probe. Icarus, 191, 251–266] that the Extremely Low-Frequency (ELF) signal at around 36 Hz observed throughout the descent, might have been generated in the upper ionosphere of Titan, driven by a plasma instability mechanism associated with the co-rotating Kronian plasma flow. The involved process was proposed as the most likely source of a Schumann resonance in the moon's atmospheric cavity, the second eigenmode of which is actually found by models to occur at around 36 Hz. In this paper, we present a thorough analysis of this signal based upon the Huygens Probe attitude data deduced from the Descent Imager Spectral Radiometer (DISR), and relevant measurements obtained from the Radio Plasma Wave Science (RPWS) experiment and from the magnetometer (MAG) onboard Cassini orbiter during flybys of Titan. We have derived several coherent characteristics of the signal which confirm the validity of the mechanism initially proposed and provide new and significant insights about such a unique type of Schumann resonance in the solar system. Indeed, the 36 Hz signal contains all the characteristics of a polarized wave, with the measured electric field horizontal component modulated by the antenna rotation, and an altitude profile in agreement with a Longitudinal Section Electric (LSE) eigenmode of the atmospheric cavity. In contrast to Earth's conditions where the conventional Transverse Magnetic mode is considered, the LSE mode appears to be the only one complying with the observations and the unexpected peculiar conditions on Titan. These conditions are essentially the lack of any lightning activity that can be ascertained from Cassini observations, the presence of an ionized layer centered around 62 km altitude that was discovered by the PWA instrumentation, and the existence of a subsurface conducting boundary which is mandatory for trapping ELF waves. A simple theoretical model derived from our analysis places tentatively consequential constraints on the conductivity profile in the lower ionosphere. It is also consistent with the presence of a conductive water ocean below an icy crust some tens of kilometers thick.
... The onboard processing of the waveform received by the electric dipole was performed with the Fast Fourier Transform technique, within two frequency ranges, namely the so-called " Schumann " ELF band (3–96 Hz, with 3 Hz resolution) and a VLF band from 180 Hz to 11.5 kHz (for detail see Grard et al., 1995). In this paper, we will focus essentially our analysis on the ELF observations since the challenge of the passive measurements was the eventual detection of a Schumann resonance similar to that observed on Earth since the middle of the last century (Schumann, 1952; for a historical review see Besser, 2006). The existence of this phenomenon would be indeed an indirect evidence of a strong lightning activity. ...
Article
The low-frequency data collected with the antenna of the Permittivity, Wave and Altimetry experiment on board the Huygens Probe that landed on Titan on 14 January 2005 have been thoroughly analyzed considering different possible natural and artificial effects. Although a definite conclusion is still subject to the outcome of complementary inquiries, it results from our analysis that the observations can be explained, for the most part, in term of natural phenomena rather than being artifacts. Extremely-low frequency waves generated in the ionosphere of Titan, driven by the corotating Saturn's frozen plasma flow, are assumed to be the most likely source for the observation of the second eigenmode of a Schumann-like resonance at around 36 Hz in the moon-ionosphere cavity. This particular mode is thought to be enhanced with respect to other harmonics because of the particular location of the landing site with respect to that of the supposed sources. The power budget of the observed wave amplitude seems to be consistent with a rough model of the global current of the wake-ionosphere circuit. Broadband low-frequency noise events which are observed sporadically during the descent are probably due to shot noise on the antenna when the Probe is crossing aerosol clouds, an interpretation supported by post-flight ground tests. Contrary to the situation encountered on Earth, atmospheric lightning does not appear to be the source of a conventional Schumann resonance on Titan.
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We present a study of the Schumann resonance (SR) regular variations (March 2013–February 2017) using the ground-based magnetometers from the Sierra Nevada station, Spain (37°02′N, 3°19′W). The study is based on the fitting parameters obtained by the Lorentzian fit, calculated for each 10-min interval record, namely, peak amplitudes, peak frequencies, width of the resonances, and the power spectrum integral for the first three SR modes. We consider three time-scales in the study: seasonal, monthly, and daily variations. The processed data collected by the Sierra Nevada station are also made public with this work. The general characteristics of the long-term evolution of the SR are confirmed, but discrepancies appear that require further study comparing recent measurements from different stations. Signatures of the influences of the El Niño phenomenon and the solar cycle to SR have been found.
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Ambient levels of nonionizing electromagnetic fields (EMF) have risen sharply in the last five decades to become a ubiquitous, continuous, biologically active environmental pollutant, even in rural and remote areas. Many species of flora and fauna, because of unique physiologies and habitats, are sensitive to exogenous EMF in ways that surpass human reactivity. This can lead to complex endogenous reactions that are highly variable, largely unseen, and a possible contributing factor in species extinctions, sometimes localized. Non-human magnetoreception mechanisms are explored. Numerous studies across all frequencies and taxa indicate that current low-level anthropogenic EMF can have myriad adverse and synergistic effects, including on orientation and migration, food finding, reproduction, mating, nest and den building, territorial maintenance and defense, and on vitality, longevity and survivorship itself. Effects have been observed in mammals such as bats, cervids, cetaceans, and pinnipeds among others, and on birds, insects, amphibians, reptiles, microbes and many species of flora. Cyto- and geno-toxic effects have long been observed in laboratory research on animal models that can be extrapolated to wildlife. Unusual multi-system mechanisms can come into play with non-human species — including in aquatic environments — that rely on the Earth’s natural geomagnetic fields for critical life-sustaining information. Part 2 of this 3-part series includes four online supplement tables of effects seen in animals from both ELF and RFR at vanishingly low intensities. Taken as a whole, this indicates enough information to raise concerns about ambient exposures to nonionizing radiation at ecosystem levels. Wildlife loss is often unseen and undocumented until tipping points are reached. It is time to recognize ambient EMF as a novel form of pollution and develop rules at regulatory agencies that designate air as ‘habitat’ so EMF can be regulated like other pollutants. Long-term chronic low-level EMF exposure standards, which do not now exist, should be set accordingly for wildlife, and environmental laws should be strictly enforced — a subject explored in Part 3.
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The potential of electromagnetic fields (EMFs) for disease treatment and health enhancement has been actively pursued over the recent decades. This review first provides a general introduction about natural EMFs and related biological effects. Then the recent progress on the EMF treatment of some common diseases (such as cancer, diabetes, wound healing and neurological diseases, etc.) has been carefully reviewed and summarized. Yet, the blindness on the selection of therapeutic EMF parameters still hinders the broad application of EMF therapy. Moreover, the unclear mechanism of EMF function and poor reproducibility of experimental results also remain big challenges in the field of bioelectromagnetics. Bionics is a useful methodology that gains inspiration from nature to serve human life and industry. We have discussed the feasibility of applying bionic approach on the selection of therapeutic EMFs, which is based on the findings of natural EMFs. Finally, we advocate that the detailed information of EMFs and biological samples should be thoroughly recorded in future research and reported in publications. In addition, the publication of studies with negative results should also be allowed.
Article
Extremely Low Frequency (ELF) electric field signals recorded by the Huygens probe have previously been interpreted as indicating a Schumann Resonance (SR) in the ionosphere-ocean cavity. This interpretation required accommodation of a number of anomalous features with respect to the terrestrial SR, namely a lack of observed lightning discharges with instead an appeal to excitation by interaction with the Saturnian magnetosphere, a horizontal field orientation, and the presence of only a single spectral peak speculated to be the second eigenmode. We suggest here that the data are dominated by artifacts due to mechanical oscillations of the booms or other elements of the probe. Although such an explanation was previously dismissed, we show in new analyses that the ELF time series correlates closely with the history of other mechanical vibration on the probe. In particular, the growth of the ‘ELF’ signals after the release of the main parachute, when the most extensive probe motions also began, and the disappearance of the signals within a few seconds after probe impact, point to a mechanical origin. We additionally review the capability of possible future SR measurements to constrain the thickness of an ice crust on Titan. Even if the magnetospheric excitation does not happen (it may or may not have occurred during the Huygens descent, we only argue that it is not required to explain the data), sporadic lightning during methane rainstorms could yet occur and excite occasional SR activity. However, the interpretation of the SR to retrieve ice thickness is challenged by ambiguities without simultaneous knowledge of the lower ionospheric structure.
Article
We present the performance characteristics of a high-sensitivity radio receiver for the frequency band 0.5-470 kHz, known as the Low Frequency Atmospheric Weather Electromagnetic System for Observation, Modeling, and Education, or LF AWESOME. The receiver is an upgraded version of the VLF AWESOME, completed in 2004, which provided high sensitivity broadband radio measurements of natural lightning emissions, transmitting beacons, and radio emissions from the near-Earth space environment. It has been deployed at many locations worldwide and used as the basis for dozens of scientific studies. We present here a significant upgrade to the AWESOME, in which the frequency range has been extended to include the LF and part of the medium frequency (MF) bands, the sensitivity improved by 10-25 dB to be as low as 0.03 fT/ Hz , depending on the frequency, and timing error reduced to 15-20 ns range. The expanded capabilities allow detection of radio atmospherics from lightning strokes at global distances and multiple traverses around the world. It also allows monitoring of transmitting beacons in the LF/MF band at thousands of km distance. We detail the specification of the LF AWESOME and demonstrate a number of scientific applications. We also describe and characterize a new algorithm for minimum shift keying demodulation for VLF/LF transmitters for ionospheric remote sensing applications.
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The chronological events in science and technology that lead to the development of the anodizing industry are presented. This chapter reviews important related interdisciplinary sciences that contributed to the discovery of passive behavior of various metals, the electrochemical formation of anodic oxide on aluminum, its characterization and development of applications. Additionally, important research and development specific to anodizing theory is provided that spans the late nineteenth and twentieth century to important research that is being carried out today is presented. The work of selected important scientists who contributed to the birth of the anodizing industry and the course of its theoretical development as well as key figures in modern anodizing are also presented.
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Schumann resonance transients which propagate around the globe can potentially generate a correlated background in widely separated gravitational-wave detectors. We show that due to the distribution of lightning hotspots around the globe, these transients have characteristic time lags, and this feature can be useful to further suppress such a background, especially in searches of the stochastic gravitational-wave background. A brief review of the corresponding literature on Schumann resonances and lightnings is also given.
Article
Schumann resonances (SR) are a set of frequencies of electromagnetic(EM) waves in the natural cavity formed by the earth's surface and its ionosphere, in the extremely low frequency (ELF) range, caused by natural electrical activity of the earth and its atmospheric environment. Because of the resonance interaction, EM energy of SR is stronger than the other frequencies'. In recent years, studies have found that earthquakes would disturb the stable parameters and spectra of SR, so using SR anomaly to implement earthquake monitoring is effective. However, finding out the EM field background variation is the basis of distinguishing the seismic EM anomaly. In this paper, utilizing ELF electromagnetic monitoring stations' natural electromagnetic field data, we processed and analyzed electromagnetic field components' power spectrum curve of SR frequencies, and obtained Schumann resonance background change with season and latitude. Comparing SR' electromagnetic field curves of one station, we can see electromagnetic field intensity changes with seasons obviously. This is weaker in winter and stronger in summer, and the amplitude of sinusoidal variation differs by two orders of magnitude. Comparing the same frequency's graphs of different stations, it is observed that electromagnetic field intensity is enhancing with the decreasing of the latitude. The background variation study will provide physical basis for distinguishing the earthquake electromagnetic animaly.
Article
The zeroth theorem of the history of science (enunciated by E. P. Fischer) and widely known in the mathematics community as Arnol'd's principle states that a discovery (rule, regularity, or insight) named after someone often did not originate with that person. I present five examples from physics: the Lorentz condition ∂muAmu=0 defining the Lorentz gauge of the electromagnetic potentials, the Dirac delta function delta(x), the Schumann resonances of the Earth-ionosphere cavity, the Weizsäcker-Williams method of virtual quanta, and the Bargmann, Michel, and Telegdi equation of spin dynamics. I give sketches of both the actual and reputed discoverers and quote from their discovery'' publications.
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The historical development of terrestrial atmospheric electricity is described, from its beginnings with the first observations of the potential gradient to the global electric circuit model proposed by C.T.R.Wilson in the early 20thcentury. The properties of the terrestrial global circuit are summarised. Concepts originally needed to develop the idea of a global circuit are identified as “central tenets”, for example, the importance of radio science in establishing the conducting upper layer. The central tenets are distinguished from additional findings that merely corroborate, or are explained by, the global circuit model. Using this analysis it is possible to specify which observations are preferable for detecting global circuits in extraterrestrial atmospheres. Schumann resonances, the extremely low frequency signals generated by excitation of the surface-ionosphere cavity by electrical discharges, are identified as the most useful single measurement of electrical activity in a planetary atmosphere.
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Es wird eine Näherungsformel für die Dämpfung der niedersten Eigenfrequenzen des Systems Erde — Luft — Ionosphäre abgeleitet, durch deren Messung die wirksame Höhe δ der Luftschicht und der wirksame Leitwert, der Ionosphäre bestimmt werden kann.
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Book
William Thomson, Baron Kelvin (1824–1907), born with a great talent for mathematics and physics, was educated at Glasgow and Cambridge. While only in his twenties, he was appointed to the University of Glasgow's Chair in Natural Philosophy, which he was to hold for over fifty years. He is best known for lending his name to the Kelvin unit of measurement for temperature, after his development of an absolute scale of temperature. This book is a corrected 1884 edition of Kelvin's 1872 collection of papers on electrostatics and magnetism. It includes all his work on these subjects previously published as articles in journals including the Cambridge Mathematical Journal and the Transactions of the Royal Society. Kelvin also wrote several new items to fill gaps in this collection, so that its coverage of the state of electromagnetic research in the late nineteenth century is comprehensive.
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Born in Germany in 1888, W. O. Schumann became a distinguished university professor, and was appointed director in 1924 of the newly established electrophysics laboratory of the Technische Hochschule (now Technical University) in Munchen. During this era, he and his staff researched the subject of electrical discharges and breakdown phenomena. Oscillations and waves in gas discharge plasmas were also studied. This latter area of research was extended to encompass related phenomena of the ionosphere. Throughout five decades Schumann remained actively engaged in scientific work until his death in 1974 at the age of 86.
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A method previously proposed for a test of the existence of ionization in the upper atmosphere has been developed, and a definite proof of the existence of echoes from the upper regions has been obtained. The echoes are present for 70-meter waves with an 8-mile base near Washington, D. C. The effective height of the layer is between 50 and 130 miles. At times multiple reflections are present. Radio fading is shown to be not only an effect of interference between the ground and the reflected waves, but also to a large extent an effect of the presence or absence of reflected waves. A seasonal variation in the effective height between summer and fall seems to exist. A smaller diurnal effect is also suspected. The height seems greater in the fall than in the summer and greater in the afternoon than in the morning. Effects of wave-length and of location have been studied. A quantitative discussion of the results enables one to eliminate too gradual distributions of electron density. The measured retardation is shown to correspond to a height greater than the actual by amounts differing for various polarizations of the refracted waves.
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Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies
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This 1893 publication is a central text in the work of the Nobel prize winning physicist Sir Joseph John Thomson (1858–1940). Intended as an extension of James Clerk Maxwell's Treatise on Electricity and Magnetism, it documents the important shift in Thomson's thinking towards the model of the atomic electric field, a theory that would eventually lead to his discovery of the electron. In Chapter 1, Thomson documents his experiments with Faraday tubes, using them to physically demonstrate a 'molecular theory of electricity'. Chapter 2 considers the discharge of electricity through gases, Chapter 3 theories of electrostatics, and Chapters 4–6 are primarily concerned with alternating currents. In addition to providing crucial insight into Thomson's evolving theory of the atom, Recent Researches underscores his commitment to experimental physics, which offers 'all the advantages in vividness which arise from concrete qualities rather than abstract symbols'.
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Experimental spectra of radio noise in the band of about 50 to 100 cycles p er second have been obtained by means of digital processing. Due to the long integration times which were used, the statistical uncer tainty in the estimates of power was reduced to about 3 per-cent (0.13 d ecibel). It was hoped in t his way to observe maximum in the spectrum dne to excitation of higher resonant modes of t he earth-ionosphere cavity (for the accuracy of these data, su ch peaks should be observed if t he Q of the cavity were 10 or greater at these fre-quencies) . No statistically significant evidence of these cavity effects was found.
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Previous authors have discussed the propagation of radio-atmospherics by assuming that the space between the earth's surface and the ionosphere behaves like a wave-guide. If the surfaces of such a guide are treated as perfect conductors, then there is one mode of propagation, the “zero-order” mode, which is unattenuated at all frequencies. In such a guide the wave-form of the received e.m.f. due to one mode at a great distance from a lightning flash can be calculated, and for modes of non-zero order it would be of an oscillatory type similar to that observed in many atmospherics from distant sources. But it would also include a large undistorted impulse due to the energy propagated in the zero-order mode, and this is not observed in practice. Moreover, recent measurements of the amplitudes of the component frequencies of atmospherics have shown that frequencies below about7·5 kc./s. are heavily attenuated during propagation from the source to the receiver, and this is inconsistent with the presence of a zero-order mode which is unattenuated at all frequencies.
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On a clear day, there is a downward electric field of 100 to 300 volts/meter at Earth&apos;s surface, although this field is not noticeable in daily life. That is, one does not encounter a 1 kV potential difference when getting into a car on an upper floor in a parking garage, and electrocution is not the major hazard associated with jumping out of trees. The major reason why we don&apos;t notice the fair‐weather field is that virtually everything is a good conductor compared to air. Objects such as tree trunks and our bodies are excellent ionic conductors that short out the field and keep us from noticing it. But the field is there. An electric current totaling one kiloamp worldwide flows from thunderstorms in the troposphere into the ionosphere and magnetosphere, eventually returning to the ground through the fair‐weather atmosphere and closing via lightning.
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Developments in the theory of radio propagation in the first half of the twentieth century are briefly traced from early work on diffraction around the curved surface of the Earth to the discovery of the magnetosphere with the aid of whistlers. Attention is drawn to the possibility that Marconi may have been initially inspired by the concept of the Atlantic Ocean as a giant cost-free telephone wire linking the European and American continents. (auth)
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Im Jahre 1952 veröffentlichte Winfried Otto Schumann, damals Direktor des Elektrophysikalischen Instituts der TU München, seine ersten Arbeiten über elektromagnetische Wellen in dem Hohlleiter, der von der Erdoberfläche und der Ionosphäre gebildet wird. Seit dieser Zeit ist das Studium dieser später als Schumann-Resonanzen bezeichneten Wellen ein interessantes Forschungsobjekt geblieben. Mit modernen Messtechniken eröffnet die Registrierung dieser Resonanzen vielfältige Anwendungsmöglichkeiten, die von der globalen Blitztriangulation, über die Erfassung von Weltraumwettereffekten bis zum Aufspüren globaler Klimavariationen reichen.
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The propagation of the slow-tail portion of atmospherics is considered from the waveguide-mode viewpoint. The source, which is a lightning discharge, is represented by a vertical dipole. The transient response of the distant electric field is then computed for various forms of the source current waveform. The results are then employed to reinterpret the experimental data of Hepburn. As suggested by the present theory it is found that the observed separation ts, between the oscillatory head of the atmospheric and the maximum of the slowtail amplitude varies with distance p to the source according to a law of the form The constant A is related to the pulse width of the source, and the constant B depends on ionospheric parameters. Values of effective ionospheric conductivities deduced from the theory are consistent with earlier results for the VLF band. The influence of nonvertical currents in the discharge channel is also briefly discussed.
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The possibility of excitation of the Earth-ionosphere cavity by hydromagnetic waves propagated through the ionosphere is investigated. Propagation through the ionosphere is studied at frequencies near the lowest resonant frequencies of the Earth-ionosphere cavity (7–30 c/s) by use of Epstein's method. In this method, certain mathematical functions are assumed as layer profiles and the wave equation is transformed into the hypergeometric equation.The analysis is based on macroscopic equations for a partially ionized inhomogeneous plasma embedded in the Earth's magnetic field. It is assumed that hydromagnetic waves are incident from above and propagated parallel to the Earth's magnetic field. Power transmission coefficients are calculated employing complex refractive index profiles which approximate those obtained from available ionospheric data. The transmission coefficients, calculated for various times of day, show that maximum transmission occurs around local midnight and minimum transmission around local noon.The various single particle and instability mechanisms which could possibly lead to generation and amplification of hydromagnetic waves in the ionosphere are briefly discussed. The expected characteristics of electromagnetic noise in the Earth-ionosphere cavity resulting from excitation by hydromagnetic waves and by worldwide thunderstorm activity are discussed.
Article
A historical account of the development of electromagnetic theory associated with the discovery of the ionosphere is presented. The topics discussed include the theory of diffraction round the curved surface of the earth, the concept of complex height, HF propagation, the Lorentz polarization correction, group velocity, the Ray-theory and associated approximations to the Wave-theory, the Exact wave theory, hydromagnetic frequencies, Whistler frequencies, problems in terminology and notation, scattering, and wave interaction.
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The paper considers E-type natural oscillations in the earth-ionosphere waveguide, taking account of the vertical profiles of lower-ionospheric plasma parameters. In addition to eigenvalues corresponding to ELF (Schumann) resonances, new resonance branches have been obtained in the lower VLF range. Excitation of the waveguide at ELF is considered and a comparison is made of resonance parameters derived from power and cross spectra in the presence of local interferences.
Article
In this paper a possible surface wave mode of propagation for the slow or tail component in an atmospheric is discussed. Surface wave solutions for the propagation of electromagnetic waves between infinite plane conductors are set up and it is shown that if one of the layers is of finite conductivity there is a solution which corresponds qualitatively with the observed velocities and periods of the slow component.
Article
The equation describing the earthdonosphere cavity resonance phenomenon is formulated in terms of reduced variables for the particular case of a twodayer model iono- sphere. Solutions for the resonance frequencies and Q factors of the resonator are given for a practical range of parameter values of the lower ionosphere and, by comparing the theoreti- cally predicted characteristics of the resonances with experimental observations, a specific model that explains world-wide propagation at extremely low frequencies is derived. Introduction. In an earlier paper, existing data on the earth-ionosphere cavity resonance phenomenon have been discussed, and it was shown how the experimental data could be in- terpreted in terms of a twodayer model for the lower ionosphere (Chapman and Jones, 1964b, c). In this paper a method of interpreting cavity resonator observations by employing reduced variables is described, and the Q factors of the resonances appropriate to a twodayer iono- sphere model are determined. The results are an extension of previous calculations based on a homogeneous model of the ionosphere (Rae- ruer, 1961; Chapman and Jones, 1964a) which predicted too low a Q factor for the resonances.