The contribution of the atmosphere in SAR interferometry is not completelyknown. Therefore, the goal of the project is to characterise the atmosphere, i.e., tostudy the way it relates to interferograms. The analysis of the atmospheric parameters that have an inuence on interferometry will cause a better understandingof the atmosphere.One of the objectives is to determine the relationship between interferogramsand the refractivity calculated on the Earth's surface, to evaluate whether variations or changes of refractivity involve a change in the interferograms.This work also deals with the analysis of the atmospheric distance of correlation. This distance indicates the maximum separation between two correlatedpoints of the atmosphere. SAR di erential interferometry uses this parameterto extract the component of phase due to the atmosphere, so the calculation ofvelocities of deformation of the land is better.