Active thunderstorms can emit gamma-rays and even antimatter. In fact, growing lightning channels can act as enormous particle accelerators above our heads. Researchers of the Multiscale Dynamics group at CWI have modelled and simulated these multiscale processes. They corrected previous calculations of gamma-ray emissions and, for the first time, computed the emission and propagation of positrons and neutrons. The neutrons are produced in nuclear reactions in air and might reach the ground.