Comments on “A New Look at the Israeli Cloud Seeding Experiments”

Abstract

Rangno and Hobbs?s (RH) paper is a scattergun attack on the Israeli rain enhancement experiments that has no basis, as shown in this comment. This approach, unfortunately, has served to complicate rather than clear up questions relating to the Israeli experiment. The only area of agreement concerns some microphysical aspects of the Israeli clouds. But even there RH and the author disagree on their ramifications for cloud seeding effects. The existence of coalescence and ice multiplication in some of the Israeli clouds in no way precludes enhancement of precipitation, even from those clouds. The claims of RH with respect to the Israeli experiments are many and varied. They claim and/or imply that (a) there is no physical basis for glaciogenic seeding in Israel; (b) the seeding was not conducted properly; (c) the experimental design was violated; (d) the evaluation was done selectively to obtain the highest effects; and (e) all the yet unexplained (by RH) seeding effects are due to type I errors (a lucky draw), twice in a row. All of RH?s arguments are refuted, as described in detail in this comment. Therefore, the following can be concluded. The Israeli I and Israeli II cloud seeding experiments were executed and analyzed faithfully according to their experimental designs. The statistical analyses are valid and done according to the experimental design. The results show significant positive seeding effects in northern Israel. The magnitude of the seeding effect is plausible with respect to operational and physical considerations. The results of the Israeli I and Israeli II experiments confirm each other. Intermediate results of the Israeli III experiment in the south are in line with the previous results there. Target?control analyses of the operational seeding that followed the Israeli II experiment in the north show yet another replication of significant positive seeding effects there. There is mounting evidence that the desert dust is responsible for the difference in the seeding effects between north and south Israel. The Israeli rain enhancement project remains an example of the strength and robustness of results that are obtained as an outcome of long-range planning in a scientific effort in the field of rain enhancement that has been continuous and consistent for three and a half decades thus far.