Experiments on light pulse communication and propagation through atmospheric clouds

This paper describes the facilities and results in an experiment to investigate light pulse propagation through atmospheric clouds. The experiments were conducted with the transmitter and receiver located on two mountain peaks in a naturally cloudy area. The transmitter was a Q-switched ruby laser producing 30 nsec light pulses. The received pulses were 1-10 microsec in duration when there was a cloud in the propagation path. The multipath time lengthening of the received pulse resulted from multiple scattering inside the cloud. The extent of this multipath pulse spreading can be shown to be comparable to that predicted from computer simulation models. We also observed a number of effects in which relatively small changes in the gross cloud shape produced a change in the received signal intensity of an order of magnitude or so.