Clouds are the key element that regulates the water cycle and the earth's energy balance. Nowadays, it is well known that the phenomena of cloud formation, droplet dynamics and turbulence are closely related; however, the reciprocal effects, descriptive and predictive models are still an open field of research. One of the reasons why the study of these phenomenologies is particularly challenging is the difficulty of being able to obtain accurate experimental data. For large scales, measurement campaigns are already being carried out, using large balloons or through appropriately equipped aircraft. For small scales, however, it is still challenging to be able to sample the characteristics of the atmosphere in a Lagrangian manner, for these reasons the COMPLETE H2020 project was born.