Abstract

In earth radiation-balance measurements in the microwave and infrared, there appeared to be more water-vapor absorption than was predicted by theoretical treatments of the absorption by single water molecules. The anomalous water-vapor absorption (AWA) has been attributed to dimers, trimers, molecular aggregates, and inaccurate treatment of far-IR water-vapor absorption.¹ We have constructed an experiment that shows that CO₂ in the presence of H₂O vapor appears to form a temporary molecular combination that could possibly cause AWA. The experiment concurs with variations observed in CO₂ monitoring stations; these variations occur as H₂O partial pressure varies. Furthermore, diffusion-coefficient measurements of CO₂ in H₂O vapor show that to satisfy Graham's law, one to two times the H₂O molecular weight must be added to that of CO₂. The atmosphere of the earth contains ~34O parts in 10⁶ CO₂ and thus is a convenient source of possible CO₂-H₂O bonding. The results of transmission measurements in 10 cm and 114 cm gas cells with a BOMEM interferometer/spectrometer will be described for various CO₂-H₂O-vapor-air mixtures.

© 1990 Optical Society of America