The auroral luminosity‐curve

The theoretical curve of luminosity produced by a bundle of cathode rays penetrating an atmosphere rectilinearly is discussed. The auroral luminosity‐curve is determined by photographic photometric methods. The luminosity‐curves observed are compared with the theoretical luminosity‐curve produced by cathode rays. The value of H = ( kT / mg ) is determined as a function of height of the maximum of luminosity. The values of H determined from studies of auroras are in agreement with the values determined independently from ionospheric studies. From filter photographs the values of H are determined independently for the luminosity in green ( G ) and violet ( V ). Using the experimentally determined values of H the density and pressure in the auroral region for various heights are computed. The curves of absorption and of luminosity for bundles of cathode rays in the range of velocities from 0.02 c to 0.9 c penetrating the model atmosphere rectilinearly are computed. The height of the anormal E ‐reflections observed during auroral displays and the position of the absorbing layer are discussed.