The atmospheric parameters have a strong impact on the image formation through the atmosphere. Indeed, the effect of atmospheric turbulence on wavefronts reduces severely the resolution of ground-based astronomical observations. Thus, in the context of astronomical observations, the site-selection has now become essential with the advent of the next generation of Extremely Large Telescopes (ELT). Indeed, it is important to choose sites with reduced cloud coverage, weak turbulence and low aerosol distribution in order to enhance observations time and to improve their scientific performance. It is also important to remember that the choice of sites hosting astronomical projects must meet very strict criteria in terms of optical quality. Future optical communications and telemetry stations will be forced to meet the same
requirements.