Excitation mechanisms of sodium night airglow.

Several known mechanisms contributing to the emission o f aodinm-D lines in the night ariglow o f the upper atmosphere are oxamincKl in detail, using tl\e recently* available information al)oiit the night-time oxygen-hydrogen atmosphere.Our results establish the following conclusions on firm footing :(i) The Chapman mechanism is almost entirely responsible for the observed peak emission at about 85-90 km.altitude.(ii) The intensity variation of sodium faithfully ff)llow those of Ozone concentration.(iii) The integrated total emission intensity is about l.^OK.These calculations are com pand with several earlier models and many finer points of the phenomena are brought out.