Based on measurements of the diffused and direct solar radiation intensity, the atmospheric lucidity and its variations that are characteristic of nebulosity. They also consider the dependence of diffused radiation on the nebulosity. In the work it was established that the atmospheric lucidity in Latvia is usually in the range of 0.77 ± 0.05, with only minor changes, so in the calculations it was assumed constant. The diffused solar radiation intensity was found to increase under medium nebulosity and to decrease at high its level. Since this dependence is also influenced by the type of clouds, for more precise calculations further research is needs.