Absorption spectra of ambient atmosphere and its major constituents (H2O, CO2, O2) were measured by means of high-sensitivity laser spectrometers in the vicinity of the Nd-YAG laser 1.06415 km wavelength. Water vapour is found to be the main absorber in this spectral range. Numerical simulations show that the narrow-linewidth radiation attenuation due to molecular atmospheric absorption varies within the laser-luminescence band from 0 to 20% along the 10 km horizontal path.