The possibility of quantum key distribution in the atmosphere has been experimentally demonstrated by coupling commercially available quantum key distribution units designed for fiber-optic communication lines with atmospheric optical communication terminals. For distances up to 3100 m, data on losses in a quantum channel on an optical path were obtained and the influence of systems for intelligent adjustment of atmospheric communication terminals on the synchronization system of quantum communication blocks was studied. It has been established that failures of synchronization systems in the case of quantum key distribution in the atmosphere at distances greater than 10 m are due to the peculiarities of the algorithm implemented in the quantum communication unit. Keywords: quantum key distribution, atmospheric optical communication lines, FSO, decoy-state BB84 protocol, polarization coding.