Global and diffuse shortwave (SW) and global erythemal (UVER) irradiances were measured in Malta, in the middle of Mediterranean Sea. The effect of solar zenith angle on these irradiances is studied using the measurements and simulations developed with a radiative transfer model. The role of ozone, scattering by gases, and aerosols is analyzed. Results show that ozone and Rayleigh scattering are the main drivers responsible for the behavior of UVER variations with SZA. In the case of global and diffuse irradiance, the role of aerosols is the principal determinant.