When UV emitter (LEDs, “black light” Fluorescent lamps, etc) and UV detector (tube or transistor) are on the same wavelength, very little power goes a long ways.

Already it is seen that a large distance is needed to get out to the to-weak-to-copy point… through clear air that is!

Today it snowed. Visibility went down to only 1500-2000 feet. UV light gets reflected back by the snow and that varies, which is hearable as if VHF FM fading in/out from DFQ to NFQ.

Snow itself, via any reflected light it gives back makes noise as it passes before the detector… a soft fluffy crumbling sound due to each snow particle passing abruptly in view – maybe like flour slowly poured on a microphone. (My wife refused to let me test that idea out, saying “NO WAY, NOT IN MY KITCHEN YOU DON”T!)

So instead of cloud bounce (an idea that was being considered by others) we have Snow Bounce – using it like a passive repeater, only more local in coverage.

Fog and rain, if heavy, does same thing but one must send on an angle, not head-on, and like for snow the receiver must be NOT on the opposite side of the snow/rain/fog area.

Snow, rain and fog reflect/refract light differently and produce different amounts of losses and what amounts to QSB.

Therefore, for this to work beyond just for experiment fun, many relay stations will be requires – or – communications will only occur when the air is clear and most certainly at night.

Sunlight (direct or diffused by clouds etc) is loaded with U.V. light, thus making a stream jet sound when aiming at a light colored object (especially those which glow bright when illuminated by UV light).

However that noise is not so bad compared to the loud buzzing that lights, run on AC, make.

Note: detector tube and its wiring must be shielded well, as if for “magnetic phono cartridge” – for anyone who remembers HIFI phonograph/turntable days.