Atmospheric boundary layer is the active link between atmosphere and the surface of the earth. Thus its ability to transport momentum, sensible heat, water vapor and other constituentes is of fundamental importance in all studies related to land surface/atmosphere as well as ocean/atmosphere exchange processes including parameterization in the global circulation model. In this work an observational and theoretical study of turbulent fluxes, temperature and humidity convergence in convective boundary layer of Fortaleza a semi-arid region of northeast Brazil is performed. For this the data of balloon soundings collected as a part of EMfiN (Experiments of microphysics of clouds) project during the period from 02-04-2002 to11-04-2002 in the city of Fortaleza N-E Brazil are used. The measurements errors of the data aquisition system are considered according to the standard deviation furnished by manufacturer. Then the temporal evolution of the temperature, humidity, wind speed and direction are plotted. The balloon sounding data are used in the thermodynamic energy and humidity conservation equations for the estimation of surface fluxes, considering that the boundary layer is horizontally homogeneous, but may be extended to include the advection terms. The results obtained show that there is a good agreement between the fluxes estimated from the sounding data using thermodynamic energy and humidity conservation equationas and profile method. So in the absence of sophisticated fast response turbulence instrumentation and micrometeorological tower measuements, the thermodynamic energy and humidity conservation equations are quite useful and reliable in that these are based on the fundamental conservation equations and measurements of mean wind, temperature and humidity profiles without any restrictive assumptions.