On Cloud-Top Determination from Gemini-5.

Abstract A hand-held spectrograph-camera has been used by the Gemini-5 astronauts to obtain spectra of sunlight reflected from clouds in the region of the oxygen “A” band near 7600 A. The transmittance measurements at selected wavelengths inside the band offered a means of measuring the amount of oxygen in the optical path, and, therefore, the cloud top altitude. Results of the observations are presented, with verification of four cases indicating the validity of the experiment. A method for computing a correction factor, needed to account for the extra absorption inside the cloud, is developed. This method gives the dependences of the correction factor on the solar zenith, viewing and azimuthal angles. Results of computations by this method are compared with earlier results based on the two-streams theory of Schuster.