The Absorption of Sunlight by the Earth's Atmosphere in the Remote Infrared Region of the Spectrum

Abstract

Spectroheliometric observations on the absorption spectrum of the Earth's atmosphere have been extended from $5\mu \mathrm{to} 21\mu$. The long wave limit of transmission imposed by the atmosphere occurs at $13.5\mu$. It is occasioned primarily by ${\nu }_2$ of C${\mathrm{O}}_2$ and to a lesser extent by ${\nu }_2$ of ${\mathrm{O}}_3$. The carbon dioxide absorption blends with the pure rotation spectrum of water vapor at approximately $17\mu$ to render the region beyond $13.5\mu$ opaque to stellar radiation.