The output of effective ice nuclei from silver iodide generators can vary by at least three to four orders of magnitude as a function of the type of generator device employed and its operational efficiency. A detailed consideration of each phase of the process of calibrating silver iodide generators shows that with care meaningful calibrations to within a factor of 1.5 are possible.
The repeatability of actual calibration experiments together with space closed volume experiments support the validity of generator testing procedures.