This report summarizes the results from a three-year research project Atmospheric effects and wave propagation that lasted 2022 to 2024. This research was funded by the Swedish Armed Forces R&D programme for Sensors and low observables (FoT SoS, AT.9220424). The project studied the impact of the atmosphere on the propagation of electromagnetic waves that is used in radar and electro optical (EO) systems. The atmosphere may, during certain conditions, cause shorter or longer detection ranges. Knowledge of the electromagnetic properties of the atmosphere and the corresponding impact on our own sensor and an opponent's sensors can be used tactically. The project explored, using numerical weather forecasts, the duration for which it is possible to predict the wave propagation properties of the atmosphere relevant for radar and EO systems. The project also investigated the most appropriate way to model wave propagation in the atmosphere. Improved prediction and propagation models provide a better foundation for assessing the performance of our own sensors and those of an opponent, particularly in terms of availability and detection ranges. Weather radar data, AIS (Automatic Identification System) messages, and collected optical turbulence data was used to validate the models.