More and more an accurate knowledge of the cloud cover is requested in various fields: weather forecast, atmospheric radiation transfer of solar UV radiations, modelling and forecasting of chronic air pollution. These data could be reached easily for macro scale by satellite but for meso and micro scale ground based measurements keep a significant interest.

For this presentation, we measured and retrieved data with various methods (Human observers, radio soundings, Total Sky Imager and Nephelometer) from various places Trappes (Yvelines, France), Verneuil en Halatte (Oise, France) and Brussels (Belgium). These data were compared in order to define their coherency and their best field of application. Moreover some interpolation tests were performed in order to improve networking possibilities with such methods. Finally some preliminary results obtained with an upgraded “Nephelometer” allowing an estimation of the cloud’s water mixing ratio and by consequence an evaluation of the cloud typology will be discussed.