  The study of the free-space distribution of quantum correlations is necessary
for any future application of quantum as classical communication aiming to
connect two remote locations. Here we study the propagation of a coherent laser
beam over 143 Km (between Tenerife and La Palma Islands of the Canary
archipelagos). By attenuating the beam we also studied the propagation at the
single photon level. We investigated the statistic of arrival of the incoming
photons and the scintillation of the beam. From the analysis of the data, we
propose the exploitation of turbulence to improve the SNR of the signal.
