In:
The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 19, No. 5 ( 1947-09-01), p. 832-846
Abstract:
Charges detonated for Army-Navy Explosives Safety Board tests in Idaho, October 1946, produced pressure waves recorded by subsonic frequency microbarographs at distances 12.9 to 452 km. Observations showed both normal and abnormal signals at 182 and 292 km, no clear abnormal signals at 141 or 89 km, no signals of any kind at 872 km. In the zone of normal audibility, average wave velocity between blast point and receiving station decreases slightly with increasing distance, and may increase slightly with charge weight; it is substantially the same as sound velocity. No consistent travel-time differences for the abnormal signals resulted from changing charge weight between 3.2 and 250 tons TNT. Neither normal nor abnormal signal strengths were predictable from charge weight. The largest abnormal signal properly recorded was a 3-cycle wave train with peak-to-peak amplitude 220 microbars received 182 km from a 125-ton blast. Interpolated to apex pressure perturbation, this signal amplitude eliminates shock wave supersonic velocity as a logical explanation for abnormal audibility. Incident angles of abnormal rays are not calculable. However, if one assumes 182 km as the descent distance for rays starting out horizontally, neglects wind effects, and accepts the apex temperatures measured by balloons, rough calculations of lower stratosphere temperatures are possible. These establish 34 km as a minimum altitude at which ground temperature is reached.
Type of Medium:
Online Resource
ISSN:
0001-4966
,
1520-8524
Language:
English
Publisher:
Acoustical Society of America (ASA)
Publication Date:
1947
detail.hit.zdb_id:
1461063-2
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