The role of collision and coalescence on the microphysics of marine fog

Cloud microphysics fulfills a fundamental role in the formation and evolution of marine fog, but it is not fully understood. Numerous studies have addressed this by means of direct observations and modeling efforts. However, collision-coalescence of aerosols and fog droplets is a process often neglected. In this study we perform an analysis of the role of particle collections on the formation, development, and microphysical structure of marine fog. It was found that collisions open a path for aerosol activation by means of collisional activation. In addition, collisions contribute to the diffusional activation of fog particles by adding water mass to the growing aerosols, making them reach the required critical radius faster. Furthermore, collisions have a homogenizing effect on hygroscopicity, facilitating the activation of accumulation-mode aerosols by increasing their diffusional growth. Collision and coalescence of aerosols and fog droplets fulfill an important role in the formation and evolution of marine fog. It opens a path for aerosol activation and contributes to diffusional activation by adding water to growing aerosols. Furthermore, collisions homogenize aerosol hygroscopicity, facilitating activation of accumulation-mode aerosols while inhibiting growth of coarse-mode particles. image