Absorption in the stratosphere by some water‐vapour lines in the v² band

A study has been made of some lines in the solar spectrum, as observed from an aircraft, due to absorption by atmospheric H 2 O 16 and H 2 O 18 . The integrated absorptances for these lines, calculated using theoretical line strengths and various water‐vapour distributions, are compared with observed values. The water‐vapour distribution which gives the best fit is one which is very dry (mixing ratio 1·5 × 10 −6 ) in the lower stratosphere, but considerably wetter (up to 5 × 10 −5 ) above 25 mb.