In this work, a barometric equation was established to relate the physical quantities of the low atmosphere: pressure, altitude, and temperature with the ratio between the Boltzmann's constant and the medium mass of molecules of the constituent gases. For geopotential altitude not superior to 33 km and assuming the medium mass of the molecule 4,809 x 10-26 kg, a medium value was obtained for Boltzmann's constant of 1,373 x 10-23 J/K
low atmosphere; Stevin's equation; Boltzmann's constant