Abstract
An extensive series of experiments was carried out to compare the performance of two cloud nucleus counters, a Static Diffusion Chamber and a Thermal Diffusion Tube, operating under quite different principles, in a wide range of field conditions and with a number of laboratory aerosols. The operating ranges of the instruments only overlap slightly; nevertheless the supersaturation vs cloud condensation nuclei (CCN) concentration spectra obtained showed rather good agreement at the range boundaries and suggest that use of the two instruments would provide a viable method of obtaining CCN concentrations in the supersaturation range 0.04 to 1.25 percent.
