Far Infrared Absorption of Atmospheric Water Vapor

The rotational spectrum of water vapor has recently been spectroscopically re- solved and analyzed by Randall, Dennison, Ginsburg, and Weber. The present deter- mination of the absorption of water vapor under atmospheric conditions is based up- on the results of these authors. Their line intensities have been used, and the mean ab- sorption of the rotational band has been calculated for a temperature range from 2000 abs. to 320° abs. The half-width has been estimated as 0.50 cm-' from the avail- able information about the width of infrared band lines. The absorption intensity at the short-wave side of the band decreases in the mean exponentially, as might be ex- pected on general grounds. For waves shorter than 33 ~ the mean fraction of radiation absorbed can be expressed by the formul