Sound Propagation in the Lower Atmosphere Available to Purchase

An account is given of experiments carried out in the lower troposphere to compare observations of audible range and of angle of descent of sound from shell bursts at various heights up to 10 000 ft with calculations made from elaborately measured temperatures and winds. In stable conditions there is satisfactory agreement. Several cases were observed of anomalous propagation in which sound rays starting upward from the source are bent back to the earth. These showed the phenomena associated with anomalous propagation on the larger scale, namely, inner and outer audibility zones, “zone of silence,” and double or multiple reception of the single pulse from the source. From the experience gained in these experiments suggestions are made for (1) observation of the time interval between components of the usual double or multiple bangs from a single pulse source and (2) observation of the sound from explosions in the air as well as on the ground to obtain more information than has been obtained hitherto from sound propagation, about temperature and wind in the high atmosphere. Rocket explosions might be used for the latter purpose.