Study of aerosol scavenging processes in atmosphere

The aerosol removal has a fundamental role because aerosol has impact on human health, on visibility and act as a condensation center for cloud droplets and ice crystals, changing cloud properties (indirect e�ects on cli- mate). In this work, di�erent removal processes of aerosol have been studies experimentally (thermophoresis, ice nuclei, cloud condensation nuclei and below-cloud scavenging), with the aim to obtain a global study of these processes. Concerning the study of thermophoresis, experiments were per- formed in microgravity conditions, in order to minimize the impact of grav- ity. Particle trajectories and consequently particle velocities were recon- structed by analyzing the sequence of particle positions. Studies on forma- tion of IN and CCN, realized through two experimental campaigns, permit- ted to improve knowledge about these phenomena. Measurements related to CCN reveal diurnal trend with lower values at about midday and higher ones during the night. Measurements of IN reveal a positive correlation between higher supersaturation with respect to ice and water values and ice nuclei number concentration. Finally, indoor and outdoor measurements of aerosol concentrations were carried out; it was found that the aerosol removal is in uenced by rainfall duration