High resolution analysis of the sun's radiation received at the ground from 9 μ to 11.6 μ

Summary A brief report on the instrumentation for observations, at the ground, in the 9 to 11.6 spectral region, in the absorption of solar radiation through the terrestrial atmosphere and of the results thus obtained for the H₂O, O₃ and HNO₃ molecules.The observations have been made at Montlouis, in the south of France, at 1650 m above sea-level. Here the pollution of the atmosphere is very low because there is no industry and very little local domestic activity.The chief aim ofM. Dionne 1], who is mainly responsible for this work, was to study the weak absorption of the terrestrial atmosphere around and beyond 10 , so observation had to be made with large air masses. For if there were excess water vapour the very weak lines might disappear through the background, owing to the water vapour itself; hence the need to observe during cold weather. Great air masses and cold weather can be obtained only on fine winter days, at about sunset. The configuration of Montlouis makes it difficult to observe at sunrise, so the time of observation was very limited.Laboratoire de Physique Moléculaire et d'Optique Atmosphérique, Station de Montlouis.