AERMOD Tech Guide

Gaussian Plume Air Dispersion Model

8.2 Estimation of Solar Insolation for Small Solar Elevation Angles

If the sun is above the horizon but the elevation is less than about 2┬░ ,eq.(5) estimates the clear sky insolation, Ro , to be negative. To avoid this situation, Ro is approximated for sola elevations less than 10 ┬░ by linearly interpolating between 0.0 W m-2 (=0┬░ ) and 141.91 W m- -2 2 (=10 ┬░ ).