Combined eye–atmosphere visibility model

The effect of the earth's atmosphere on the visibility in the nadir direction, as determined by the human eye, is presented. The visibility characteristics can be obtained from the combined eye-atmosphere modulation transfer function. This function is applied to the calculation of visibility thresholds of an area of an albedo different from its surroundings. It is shown that the atmospheric effect of diffusing sharp boundaries between adjacent areas has a significant influence on the visibility threshold. A sensitivity study is carried out to investigate the effects of different atmospheric optical conditions on the visibility thresholds. This model emphasizes the use of a combined eye-atmosphere theory to predict visibility conditions from airplanes.