The continental- and global-scale spreading of pollutants emitted from volcano eruptions or industrial accidents is an everyday issue in our life. Nevertheless, students are generally not aware of the fact that pollutant clouds do not spread in the atmosphere like dye blobs on clothes, rather an initially small and compact pollutant cloud becomes soon strongly stretched, while becoming filamentary and folded. This paper introduces an application called Replat-Chaos-edu by means of which students can investigate the characteristics of the atmospheric dispersion of volcanic ash clouds and other pollutants in an interactive way. The simulations utilize meteorological data and follow the time evolution of pollutant clouds consisting of a large number of individual particles. Replat-Chaos-edu is also a suitable tool for studying the so-called chaotic features of the advection. The software was tested at the Berzsenyi Dániel Grammar School and the Szent István Grammar School (Budapest, Hungary) in the framework of Physics classes and during a project week, respectively.