Slitless spectra of lightning in the region from 3850 to 6900 Angstroms

Recent slitless spectra of the lightning flash have revealed the presence of ionized argon. The instrument used consisted of a transmission diffraction grating in front of an f/6.0 Aero-Tessar lens of 61-cm focal length. One intense lightning flash has been recorded which produced a spectrum from 3850 to 6900 A with a dispersion of 25 A/mm. A survey of nearly 200 spectra shows that molecular bands attributed to CN and N2+ in the region 3800 to 4000 A appear infrequently and with highly variable intensity. The first time-resolved spectra of the lightning flash have been obtained. No outstanding differences between the spectra of components in a given flash have been found, except for the occurrence of a continuing luminosity. No lines due to doubly ionized atoms have been reliably identified.