The wavelength dependence of atmospheric extinction

Atmospheric extinction coefficients determined at Flower and Cook Observatory for the Johnson B and V spectral responses are compared with the predictions of two models based on theoretical and observational parameters. Some of the observed deviations from the models can be explained as telluric line absorption in the wavelength region of the V response. The remaining differences arise from the use of different observational data in calculating the Rayleigh attenuation coefficients and the ozone attenuation coefficients, and local differences in the characteristics of the atmosphere. High and variable extinction coefficients seem to show an individual wavelength dependence and a periodicity with respect to time.