The green oxygen line 5577 Å in the mediumE-F andF regions during the night

Summary In this paper the contribution of theF region to the green oxygen line 5577 Å glow is investigated. It is shown that at calm nocturnal conditions the ions' O ₂ ⁺ dissociative recombination leads to a simultaneous excitation of the red and green lines in this region. It has been found that the intensity of the green line in theF region is about one-third that of the red line. By this non-negligible component we can explain some unexplained phenomena in the behaviour of the green line during the night.