New Values for the Infrared Absorption Coefficient of Atmospheric Water Vapor

Some t,ime ago the wriber examined those features of atmospheric radiation whic,li ensue from the fact, that the water va,por spectrum is a line spectrum a.nd not a continuous spectrum (1). At, that time it was not possible to give a qumtitative redetermination of the absprphion, since our spectrosaopic knowledge of the far infrared region was not sufficiently aclvance~d. In the meanbime., the work of Randall, Dennison, Ginsburg, and Weber (2) has furnished us wit,li a comple.t,e analysis of the far infrared line spe.ctrum of water vapor covering the whole spectrum beyond a wave length of 1Sp. These aut'hors have been able for the first t'ime to resolve t,he spectrum complet,ely into its individual lines; the wave lengths of the lines have been mea.sured and their int,ensities, which are difficult to measure directly, have been det,e,rrnined by calculations based upon the quant8um the.ory of the miter molecule. On t,he basis of these important result,s, in combination with the rest of our knowledge of the water spectrum, it has now become possible to obtain improved numerical va.lues for the absorption coefficient of atniospheric water vapor and its de.pende,nce upon pressure and temperature. Our calculations a.pply not only to the pnrt of the spectrum cowred in reference (2), but to the whole range of the infrared spectrum where the tlie,rnin.l radiation of the atmosphere and ground is appreciable. We might notice here that' t8he necessity for taking the line structure of the wat,er spectrum int,o account8, in dealing with problems of atniospheric ra,cliat,ion, has been pointed out several years ago by F. Albre.cht (3).