Effect of environmental factors on solar UV measurements

For a correct understanding and interpretation of solar UV data sampled at ground level, several practical and theoretical problems of measurement are shown. In particular, the comparison between either different sites or instruments is thoroughly analysed, and the effects due to O3 level, albedo and cloudiness are discerned. The impact of clouds and their position with respect to the sun on the observation carried out both by spectral and broad-band instruments are also examined.