"In our working group, we mainly deal with the theoretical investigation and modeling of atmospheric plasmas. This involves everyday phenomena that we are all familiar with, namely clouds and lightning. Although these have been known for thousands of years, we still have a very crude understanding of the processes within a cloud. Using newly developed methods, we simulate the processes that take place in a thundercloud. We focus on electrical charge processes that develop into lightning and on so-called Terrestrial GammaRay Flashes (TGFs), beams of X-rays and gamma rays, which are among the highest-energy processes on Earth. We also look at plasma chemistry and want to understand how thunderstorms contribute to the production of greenhouse gases and to the formation of prebiotic molecules on the primordial Earth and on exoplanets outside our solar system. With this research, we are helping to understand the effects of thunderclouds on technology and nature. We also deal with astrophysical processes with a focus on the spacetime structure of the universe and the modeling of processes around compact objects such as neutron stars and black holes. The aim is to understand how the spacetime of the universe is structured and what consequences arise from extended spacetime. We also use numerical models to understand fundamental questions such as the production of the highest-energy particles around compact objects."