The interaction between the land and the atmosphere is realised through the turbulent exchange of momentum, heat and moisture at the ground surface, so the structure of the stratified atmospheric boundary layer plays an important role in the studies of hydrological cycle and weather prediction. In this work some aspects of the structure of the stratified boundary layer of Fortaleza a semi-arid region of N-E Brazil, using the balloon sounding data collected in the field experiment EMfiN (experimento de microfisica de nuvens -experiments of microphysics of clouds)conducted by Universidade Estadual da Ceara-UECE, are analysed. The measurements errors of the data aquisition system are considered according to the standard deviation furnished by manufacturer The computed stress profiles and the proportionality constant in the inverse relationship between the non-dimensionalized convective boundary layer height and the square root of the stability parameter agree well with the results obtained by other authors.