Cyclotron maser emission is a powerful mechanism producing coherent and consistent radiation. It was observed from many Brown Dwarfs, and a search for observing it from exoplanets is ongoing. Such an emission can be indicative of high value dipole/multipole magnetic field and existence of accelerated electrons. We look here at a possibility to ‘use’ such emission as a probe signal for ongoing atmospheric processes. In particular, we model how flash ionization processes, like, e.g., lightning or explosion, can transform a pre-existing radiation coming through the transient region. Our modelling is based on a flash-like change of conductivity in time, with fully electromagnetic transformation of the field found exactly. We compare our model for transient conductivity to existing measurements for field and current for terrestrial discharges, in particular Terrestrial Gamma Ray Flashes. Our results demonstrate influence of the flash ionisation processes on the pre-existing field, and we provide analysis towards a possibility of observing such extreme processes’ signatures.