Figure 6
Probability of a photon to be transmitted through the atmosphere with respect to zenith angle, θ , and various optical depths, d. Increasing the optical depth, d, has the effect of reducing the peak probability of transmission. An optical depth, d, of 0.5 corresponds to high levels of pollution. Further calculations assume \(\mathrm{d}=0.37\), giving an atmospheric transmission probability of 0.69 at zenith.