The Israel 4 Cloud Seeding Experiment: Primary Results

Yoav Benjamini, Amir Givati, Pavel Khain, Yoav Levi, Daniel Rosenfeld, Uri Shamir, Ayal Siegel, Assaf Zipori, Baruch Ziv, David M. Steinberg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


After 38 years of operational cloud seeding for rain enhancement in northern Israel, the Israel 4 experiment was conducted to reassess its effect on rainfall and provide a basis to evaluate its utility. Operational seeding started after two randomized experiments, the second ending in 1976, found a large and statistically significant effect of cloud seeding on rainfall. Observational studies in later years raised doubts as to the magnitude of the effect, possibly because of chang-ing climatological conditions. A carefully designed randomized experiment was conducted from 2013 to 2020. A unique feature of the design was the use of forecast rainfall on target, rather than rainfall in an unaffected area, as a control variate to attenuate variability. The Israel 4 experiment was stopped a year earlier than planned, because the result was disap-pointing: a 1.8% increase, p value 5 0.4, and 95% confidence interval of (211%, 16%). These results led to a decision by the Israel Water Authority to stop operational seeding.

Original languageEnglish
Pages (from-to)317-327
Number of pages11
JournalJournal of Applied Meteorology and Climatology
Issue number3
StatePublished - Mar 2023


FundersFunder number
Israel Water Authority


    • Cloud seeding
    • Experimental design
    • Orographic effects
    • Weather modification


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