ABSTRACT
This chapter provides a survey of the various ionic processes that occur in the atmosphere. It starts by discussing how charged particles are produced and lost in the atmosphere. A short discussion follows on how in situ measurements are made. The chapter then presents the results of the in situ measurements. Instead of showing the results of individual measurements, a composite of the measurements is assembled where the main families of ions can be identified without distraction from minor species. The chapter also presents a discussion of the ion chemistry of atmospheric ions. The instruments can yield information on the ion chemical evolution of the atmosphere, as well as information on trace gases involved in the chemistry. The chapter discusses the general processes and provides details of the positive and negative ion chemistry. It ends with a discussion of how ion composition measurements are used to derive concentrations of atmospheric trace neutrals.
