Leipzig. The fluorescence lidar technology does not only enable a better determination of the origin of particles in the atmosphere. The method can also visualise particle layers that were previously practically invisible. This is the conclusion drawn by a team from the Leibniz Institute for Tropospheric Research (TROPOS) from the evaluation of 250 hours of lidar measurements over Leipzig in 2022 and 2023. The researchers had repeatedly observed very thin layers of smoke at high altitudes, which originated from forest fires in Canada but could not be seen using conventional methods.