Cosmic-ray-produced electrons and gamma rays in the atmosphere

The propagation of the primary cosmic radiation through the earth's atmosphere is a phenomenon of considerable intrinsic complexity stemming from the large number and variety of parameters involved and their dependence on energy, latitude, and atmospheric depth. Although in the past the study of the hadronic component in the atmosphere has received appreciable attention, not much interest has been focused on the electron‐photon component until very recent years. As a consequence, the observational data now available on the latter are meager and fragmentary; such information as is available is reviewed here, and the existing gaps in our knowledge are highlighted. Because of the very complexity of the problem, it has been recognized that extensive and refined calculations are needed to understand the observations and to provide new motivation to experimenters. In the present article the limited theoretical calculations so far attempted are first reviewed; a summary of detailed calculations recently carried out by the present authors follows. Finally, the results from the calculations are compared with those available from experiments; wherever it is necessary, attempts are made to identify the areas in which further work is needed.