Exploring the Outer Atmosphere with Lightning Flashes

G. McK. Allcock of D.P.L. Some lightning flashes produce radio signals at audio frequencies which are guided by the earth's magnetic field through the outer atmosphere. From the study of the characteristics of these signals, which are called "Whistlers," one can infer some of the physical properties of the outer atmosphere to distances of several earth's radii. Results of investigations on a global scale during the past few years will be presented and discussed.