Aerosols are dynamic systems and the kinetics of the processes that particles undergo may have timescales from milliseconds to months. However, most aerosol analysis instruments make measurements on individual particles as they pass through a microscopic measurement space and these transits last of the order of microseconds. Dynamic processes can only be studied by a series of snapshots on randomly selected particles. This is very likely to be unsatisfactory where the objective is to understand the very complex chemical and physical interactions between particles and the gaseous medium.