The fight against hailstorms in Italy, 1950–70: a long history of confirmation bias

This article analyzes the experiments for hail suppression by means of exploding rockets in Italy, where a remarkable national program of active defense was undertaken in the period 1950–70. The history of the trials of this technique is reconstructed in view of highlighting the methodological flaws of the entire experimental approach. A supplementary source of information is offered by about 1,600 “storm postcards”: reports sent back by farmers after single weather events. An archive of these postcards, recently collected, digitized, and analyzed for the Trentino region (northern Italy), offers an interesting glimpse into the scientific and pseudoscientific approaches to a difficult to predict and volatile phenomenon, both for farmers and for appointed experts.