Contrails are clouds that form behind aircraft due to water vapor and exhaust fumes. They look different depending on how much movement there is in the air and how high the planes are flying. Conspiracy theorists believe that trails that are unusually shaped or remain in the air for a long time have been mixed with chem- icals – hence the term chemtrails. The poisons are sprayed on behalf of a secret elite with the aim of controlling people‘s minds. Or to slowly poison them – supporters of the theory are not in complete agreement on this. Nor can they explain plausibly how such a global conspiracy could be implemented practically and logistically. From a scientific point of view, the theory is unfounded and rather absurd.