Acoustic Gravity Waves In The Atmosphere

The purpose of this research was to obtain a panoramic view of acoustic-gravity-wave motions throughout the atmosphere. A one-dimensional array of particles and springs, conceived by Newton to study sound waves in the atmosphere, was extended to two dimensions by means of 1500 particles interconnected by springs. Variations of density and pressure with altitude are represented by variations in mass and spring constants. This new model has provided means by which acoustic-gravity-wave motions in the atmosphere are solved on a high-speed digital computer, and a new animated-computer-output technique is used. A motion picture--automatically plotted by the computer, a frame at a time--provides greater detail and perspective of mechanical wave motions in the atmosphere than has ever been obtainable before. Ground-level and 100-km-high explosions were investigated with this computer model, and the resulting transient motions of the atmosphere were displayed by means of a motion picture produced by digital techniques. Computed ground-level barograms resulting from a ground-level explosion compare well with experimental barograms recorded during ground-level nuclear explosions. (Author).

The generation of acoustic and internal gravity waves in the earth's atmosphere by nuclear detonations is considered. Attention is given to a general statement of the problem and to the assessment of the importance of various generation mechanisms in the flows produced by nuclear explosions. From the significant source mechanisms, the corresponding wave emissions are estimated with reference to nuclear detonation outputs. (Author).

The use of infrasound to monitor the atmosphere has, like infrasound itself, gone largely unheard of through the years. But it has many applications, and it is about time that a book is being devoted to this fascinating subject. Our own involvement with infrasound occurred as graduate students of Prof. William Donn, who had established an infrasound array at the Lamont-Doherty Geological Observatory (now the Lamont-Doherty Earth Observatory) of Columbia University. It was a natural outgrowth of another major activity at Lamont, using seismic waves to explore the Earth’s interior. Both the atmosphere and the solid Earth feature velocity (seismic or acoustic) gradients in the vertical which act to refract the respective waves. The refraction in turn allows one to calculate the respective background structure in these mediums, indirectly exploring locations that are hard to observe otherwise. Monitoring these signals also allows one to discover various phenomena, both natural and man-made (some of which have military applications).

Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 18. I am advised that a preface, though not necessary, would at least be conventional. Since this provides the one opportunity for conventionality that the volume as a whole opens up, it would be churlish of me to decline. A preface normally includes, I am told, an indication of both the reason that underlies the volume's very existence and the individuals to whom the volume is directed. But part of the reason for the volume's existence lies, strange though it may seem, in communicating the reason for the volume's existence. Since prefaces generally go unread, I would be remiss if I attempted that communication here. Instead, I have left the attempt to the Introduction and Key, which I believe has a better chance of being read. Let us be willing to settle, for the moment, on the truly fundamental fact that the volume was prepared because I was prepared to prepare it and a publisher was prepared to publish it. As to the intended readers; they too, must wait for their identification in the Introduction and Key, unless they are willing to settle at this point on an identification as those who might be ready to read what I was prepared to prepare.