Abnormal Sound Propagation Over the Southwestern United States

Abnormal propagation of sound in the east‐to‐west and west‐to‐east directions has been studied throughout a period of a year. Experiments were carried out over the California‐Arizona desert using explosions of 1200 pounds of TNT. Returns of sound from altitudes of 30 to 50 km were consistently received to the east in winter and to the west in summer. Sounds which traveled to the high temperature region at 80 to 100 km altitude were received about one‐fifth of the time. Sounds were returned from the second region somewhat better to the east ha summer and to the west in winter. An early arriving abnormal wave was received at ranges greater than 400 km.