Showing papers on "Solar eclipse published in 1978"
TL;DR: The model predicts, and observations confirm, that the zenith has the highest blue-red ratio (color temperature) and lowest brightness of any place in the sky during totality, and it nevertheless correctly predicts the major observed features of the eclipsed sky.
Abstract: This paper describes a radiative transfer model for estimating the brightness or radiance of the sky during a total solar eclipse. The model is approximate; it only considers sunlight that diffuses into the umbra by first- and second-order scattering processes. It nevertheless correctly predicts the major observed features of the eclipsed sky including reddening of the horizon and lowering of zenith radiance over the normal day value by approximately 4 orders of magnitude. The calculated absolute zenith radiance at blue wavelength is about 20% lower than observed during the 1973 African solar eclipse. The model predicts, and observations confirm, that the zenith has the highest blue–red ratio (color temperature) and lowest brightness of any place in the sky during totality.
30 citations
TL;DR: In this paper, four microbarographs were used in an attempt to detect atmospheric pressure oscillations that were expected to accompany bow waves associated with the total solar eclipse of 23 October 1976, and these internal gravity waves were found to have a peak-to-peak amplitude of 0.1 to 0.2 Pa, a period of 23 min and a velocity of 3.1×102 ms−1.
Abstract: DURING a solar eclipse, the Moon's cool shadow, moving with supersonic speed through the Earth's atmosphere, should generate bow waves. In the experiments described here four microbarographs were used in an attempt to detect atmospheric pressure oscillations that were expected to accompany bow waves associated with the total solar eclipse of 23 October 1976. These internal gravity waves were found to have a peak-to-peak amplitude of 0.1 to 0.2 Pa, a period of 23 min and a velocity of 3.1×102 ms−1.
26 citations
01 Sep 1978
TL;DR: In this paper, the 12 November 1966 solar eclipse has been modeled by a large multi-species chemistry code and the results compared with the numerous experimental measurements which were made at that time, and good agreement between measured preeclipse values of electron density and code-predicted values is obtained when ionization by precipitating electrons from the radiation belts is included.
Abstract: : The 12 November 1966 solar eclipse has been modeled by a large multi-species chemistry code and the results compared with the numerous experimental measurements which were made at that time. Good agreement between measured preeclipse values of electron density and code-predicted values is obtained when ionization by precipitating electrons from the radiation belts is included. The current gas-phase ion chemistry does not predict the rapid decrease and subsequent reconstitution of the electron density about totality in the 65 to 85 km region, nor does it produce the large amounts of negative ions about 70 km which can be inferred from the experimental data. While basic constraints can be placed on the electron attachment processes because of the experimental data, an entirely new class of physical processes may possibly need to be included to explain this phase of D-region behavior. Comparison with experimental data provides a means of validating the basic atmospheric modeling computer codes which are used as input for Army communication systems and in the Army nuclear weapons effect community. (Author)
16 citations
01 Jan 1978
TL;DR: The ideas that the Earth's rotation was non-uniform and that the orbital motion of the Moon was accelerated were conceived more than two centuries ago as mentioned in this paper, but a sound grasp of the whole problem has only been realised in the last few decades.
Abstract: The ideas that the Earth’s rotation was non-uniform and that the orbital motion of the Moon was accelerated (two of the themes central to the present conference) were conceived more than two centuries ago. However, a sound grasp of the whole problem has only been realised in the last few decades.
12 citations
TL;DR: In this article, the Paris Pseudo-Galen frontispiece-miniatures are explained as a reference to the pseudoplanetary nodes of the moon's orbit, the Arabic al-Djawzahr which were regarded as the Head and Tail of a giant Dragon.
Abstract: A lunar emblem framed by a pair of entwined dragons is repeated twice on the double frontispiece-miniatures of the Arabic Pseudo-Galen manuscript in the Bibliotheque Nationale, MS arabe 2964, in Paris. Bishr Fares who discovered the manuscript argued for a relationship between the subject matter of these frontispiece-miniatures and the content of the text of the manuscript which dealt with the effects and treatment of snakebite. The present paper intends to demonstrate the astrological meaning of the theme of the Paris Pseudo-Galen frontispiece-miniatures which gains significance from the juxtaposition of the entwined dragons and the lunar emblem. The motif of the entwined dragons in these miniatures is here explained as a reference to the pseudoplanetary nodes of the moon's orbit, the Arabic al-Djawzahr, which were regarded as the Head and Tail of a giant Dragon. The astronomical importance of the jawzahr lay in its role in effecting solar and lunar eclipses which were attributed to the occurrence of a conjunction of the sun or moon in or near the lunar nodes. It is unlikely that the artist of the Paris Pseudo-Galen miniatures attempted to establish a connection between the eclipse phenomenon and the content of the manuscript. However, the correspondence between the date of the completion of the manuscript and the occurrence of a solar eclipse on January 28, A.D. 1199, would appear to indicate the astrological significance of the eclipse for the completion of the work.
11 citations
TL;DR: In this article, total electron content observations were taken on a triangular array to investigate travelling ionospheric disturbances induced by the solar eclipse of 23 October, 1976 over south-eastern Australia.
7 citations
Journal Article•
4 citations
01 Mar 1978
TL;DR: The 26 February 1979 solar eclipse provides an opportunity for controlled experiments to help differentiate among the several processes of D-region ionization as discussed by the authors, one major concern is whether the sources of ionization are largely solar or predominantly due to particle precipitation.
Abstract: : The 26 February 1979 solar eclipse provides an opportunity for controlled experiments to help differentiate among the several processes of D-region ionization. One major concern is whether the sources of ionization are largely solar or predominantly due to particle precipitation. Of equal importance are the electron attachment and detachment processes which determine the free electron densities. Comparisons of current gas-phase ion chemistry calculations with scattered available data show serious discrepancies for electron density variations above 70 km. The inclusion of a new class of reactions involving aerosols or particulates would seem to be indicated. A correct determination of D-region electron densities and electron attachment and detachment processes is necessary for proper utilization of Army communications systems and a better understanding of the effects of nuclear weapons in the middle atmosphere. (Author)
4 citations
TL;DR: In this article, the authors reported the observation of quasi-periodic fluctuations in Faraday rotation angle Ω and the 1 MHz modulation phase delay φ of 40 MHz transmissions from ATS-6 geosynchronous satellite recorded at Trivamdrum (dip 0°57′S, geographical longitude 76° 57′E) during the partial solar eclipse on 29 April 1976.
Abstract: CHIMONAS and Hines1,2 have suggested that a solar eclipse might generate gravity waves in the atmosphere. During solar eclipse the localised cooling of the atmosphere in the lunar shadow causes an energy imbalance and the shadow moving at supersonic speed across the Earth's surface could be a continuous source of gravity waves propagating to great distances in the atmosphere. These quasi-periodic wave perturbations in the ionospheric electron density, caused by the coupling between the ionised and the neutral particles, have been detected by various investigators3–5 at middle and high latitude stations away from the path of the eclipse shadow. Hajkowicz6 has reported the observation of perturbations of quasi-peniods of less than 2 min, after the October 1976 eclipse. We report here the observation of quasi-periodic fluctuations in Faraday rotation angle Ω and the 1 MHz modulation phase delayφ of 40 MHz transmissions from ATS-6 geosynchronous satellite recorded at Trivamdrum (dip 0°57′S, geographical longitude 76°57′E) during the partial solar eclipse on 29 April 1976. φ directly gives columnar electron density integrated along the radio ray path from the satellite to the receiver; whereas Ω gives columnar integrated electron density only up to an altitude of 2,000 km because of the weightage by the component of the geomagnetic field along the ray path. For ATS-6 to Trivandrum ray path geometry, a change of 10° in Ω will be produced by a change of 0.47×1016 el. m–2 of electron (el.) content. In contrast to this, 10° change in φ will be produced by a change of 0.34 × 1015el. m–2. The accuracy of measurement of both Ω and φ is better than 1°.
4 citations
01 Sep 1978
TL;DR: In this article, the field strength of atmospheric electricity was measured by means of a newly conceived measuring device showing great dissolving power during a solar eclipse on the island of Kos in the Aegean Sea, and meteorological effects on the electric field strength in Vienna were discussed.
Abstract: The field strength of atmospheric electricity has been recorded by means of a newly conceived measuring device showing great dissolving power. Recordings made during a solar eclipse on the island of Kos in the Aegean Sea, and meteorological effects on the electric field strength in Vienna are discussed.
TL;DR: In this article, the magnetic observations of a line of ten temporary stations stretching from a region of fifty percent obscuration to the path of totality were recorded, and the magnetic conditions at the time were mildly disturbed.
TL;DR: In this article, the Doppler shift of HF transmissions over south-eastern Australia during the 23 October, 1976 solar eclipse was observed using the ionosphere and the F-region.