The eleven papers presented in this issue are intended to provide a comprehen sive description of the cloud systems studied during the Kleiner Feldberg experi ment. The first paper provides a general overview of the experiment and a summa ry of the main accomplishments. The following three papers then describe the cloud systems from the meteorological, microphysical and chemical perspectives. Another four papers address more specifically the issues of incorporation of aerosol particles and trace gases within cloud droplets. A synthesis of the Kleiner Feldberg cloud properties and a comparison...