Further data concerning the distribution of water vapour in the stratosphere

The variation of the infra‐red solar spectrum with altitude was observed during a balloon flight made on 24 March 1964, from Alamogordo, New Mexico. A water vapour mixing ratio profile determined on the basis of the variation with altitude of the infra‐red solar spectrum in the vicinity of 3,854 cm −1 during this flight is presented. This profile is in agreement with the view that the mixing ratio in the vicinity of the tropopause is about 2.10 −6 g g −1 ; however, it also indicates that the mixing ratio increases again above 65,000 ft.