An intense flux of ions and electrons from the jovian magnetosphere both alters and erodes Europa's surface, producing a tenuous atmosphere. This chapter discusses the physical processes that create and remove the atmosphere, such as ion erosion (sputtering), radiation-induced chemical alteration of the surface (radiolysis), and atmospheric loss processes such as ionization and pickup. Special emphasis is placed on ongoing modeling efforts to connect atmospheric properties to surface composition. Models are at present constrained by a small number of observations, but a future mission to Europa has the potential to detect even trace atmospheric species.