Considering radiosonde-observed lower atmosphere air temperature and specific humidity data in support of isolated tall building＇s air conditioning (AC) planning, is suggested. Procedures to process such data and several illustrations of their utilization for summer afternoon meteorological conditions are provided. The constraints involved with the utilization of radiosonde data are discussed. Coastal and continental locations in the US, as represented by San Diego and Oklahoma City radiosondes, were considered for illustration. In San Diego, a significant decrease with height in air temperature, specific humidity and, consequently, ventilation load are typical. These characteristics are suggested to be typical for near shore areas of California. For Oklahoma City, air temperature typically decreased moderately with height. Specific humidity frequently increases, resulting in a mild dependence of the specific moist enthalpy on height. (C) 2000 Elsevier Science S.A. All rights reserved.