Figure 7: Frequency of gradients of the global irradiance in Carpentras, France (2001). As in Figure 6, the differences of the models for gradient values of less than 10 W/m² are comparable. In the range of 10 to 100 W/m², the new model (blue) shows a better congruence with the measured data (black) than the models of Aguiar and Skartveit (grey), while only the model of Aguiar fails to produce good congruence for gradient values of more than 100 W/m².