Meteor Whistles

Abstract

MANY observers have reported Doppler-effect heterodynes in the background of received high-frequency broadcast signals. The accepted explanation of the whistles is that waves received after reflexion from ionized meteor trails have undergone a frequency-shift, relative to the waves received by a more direct path. Usually, the pitch of the heterodyne descends to zero. Chamanlal and Venkataraman¹ suggested, in 1941, that the descending pitch was the result of the meteor being rapidly retarded in velocity. More recently, Sir Edward Appleton and Mr. R. Naismith² proposed an alternative explanation of the change of pitch, which is ascribed to the reduction of the difference between the two path-lengths that occurs as the meteor, travelling tangentially to the observer, approaches the minimum distance.