This paper concerns the characterization of clouds on meteorological satellite image sequences through points trajectories. These temporal curves can be computed from the result of motion estimation over image sequences. The study includes a representation method for the trajectories, which is based on normalized Fourier modules. The original trajectories can be compared independently of their localization, orientation and scale. We then determine that the information contained in these representation vectors is relevant for discrimination and classification of cloudy structures on satellite data. Results addressing METEOSAT infrared data are analyzed and displayed throughout the paper