Cooling towers are often located in areas where a visible plume is objectionable. In such situations, a plume abated cooling tower is frequently specified to alleviate the perceived problem. The paper discusses the use of fogging frequency analysis to examine alternative designs of plume abatement systems and the selection of the psychometric design point that defines the envelope of conditions in which a visible plume or fog is produced. This paper also examines the limits of plume abatement technology to reduce the frequency of visible plumes. The type of meteorological information to be used as design basis for plume abated cooling towers is specified.