This research includes a detailed study of the daily and monthly changes to the intensity of total solar radiation in the city of Homs (34.75N °, 36.7 E °), and a direct measurement of the intensity. The study shows that intensity increases to maximum values in summer 1100w / m2, and drops to lesser values in winter 600 w / m2. The difference between the measured values in summer and winter is due to: a change in the inclination of the sun, and implicitly solar azimuth z. This angle is at its greatest in winter and the optical path is at the maximum. Thus, the processes of scattering and absorption increase. In summer, the inclination angle is at its lowest and the optical path is at the minimum. Thus, the absorption and scattering of solar radiation are at the minimum.