Abstract

A study was made of the total absorption of five water vapor bands between 1μ and 7μ, using a multiple-reflection absorption cell in which optical path length, water vapor density, and total pressure could be varied independently. Absorption was determined as a function of these parameters. For the range of concentrations studied it was found that the fractional absorption of an entire band can be represented by an error-function formula

where $t=\frac{1}{2}\beta {(\pi w)}^{\frac{1}{2}}{(P_T+P_P/760)}^{\frac{1}{4}}$. Here w is the water vapor concentration, P_T the total pressure, and P_P the partial pressure of the water vapor. The quantity t in this formula is very nearly proportional to the fourth root of the pressure. Values of the “generalized absorption coefficient” β are determined for the five bands.

© 1952 Optical Society of America

Total Absorptance of Water Vapor in the Near Infrared

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Adiabatic pressure dependence of the 2.7 and 1.9 μm water vapor bands*

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