Optical spectral characteristics of sprites

Abstract

A TV slit spectrograph was used to obtain the first optical spectra of sprites. Twenty‐five events were observed over a thunderstorm on the border of Nebraska and Colorado on the night of 22 June, 1995 between 0700 and 0900 UT. For 10 of these events optical spectra were measured in the wavelength range from 540 to 840 nm. After correcting for the spectrograph response function, digitized spectrograph video images are used to measure the wavelengths of and ratios between the emissions. All emissions are found to be of the first positive bands of N 2 . There is no evidence of the Meinel bands of N 2 + indicating that the mechanism responsible for sprites produces little or no ionization at 70 km altitude.