Atmospheric muons represent the primary component of cosmic radiation detected at sea level. Their specific characteristics - natural abundance, energy-based ability to penetrate objects, harmlessness - make them an essential tool for performing non-destructive imaging of the internal structure of objects by means of muon transmission radiography (MTR), a 2D technique optimized for studying large objects such as mountains and volcanoes, and multiple scattering muon tomography (MSMT), a 3D technique exploited for relatively small objects. On the other hand, the considerable presence of atmospheric muons and secondary particles produced by them influences the measurements of low background experiments, designed to reveal dark matter and neutrinos signals. In all cases, the need to have a reliable model that accurately describes the energy spectrum and the angular distribution of the flux of atmospheric muons at sea level is evident. This contribution will describe the development of a parametric analytical model built by fitting a selected set of empirical models developed in the last decades to the data measured by ADAMO (Florence, Italy, 2004) and other experiments. The developed model was subsequently used as a generator tool for Monte Carlo simulations in some applications of the MTR technique and the results will be presented and discussed.