Catalonia asks the public for help studying hail: keep it in the freezer

The Servei Meteorològic de Catalunya asks the public to collect large hailstones, freeze them and thereby collaborate in pioneering research on this extreme phenomenon. Under the name #meteocatpedra, the initiative seeks to better understand how hail forms and improve forecasting systems.

Participation is simple: if hail falls nearby, people should take a photo of the stones next to a coin or ruler, add the location, date and time, and send it to Meteocat via social media or email. If the stones exceed 5 centimetres, meteorologists ask that they be kept in separate bags inside the freezer. Later, a team will come and collect them.

In addition to visual analysis, an annual observation map will be produced by combining citizen data, hail sensors and the network of weather observers. Catalonia, one of the regions most active in participatory meteorology, thus becomes an open laboratory for understanding a phenomenon that can affect everything from crops to infrastructure.