Photoelectric visibility and measurement device for cloud base.
In the times of the Polish People's Republic, various meteorological instruments were used in the military aviation to determine the visibility and base of clouds. Visibility was measured with photometric or photoelectric instruments. Photometers, i.e. optical visibility-measures, included visibility-meter by Sharonov, diaphanoscope by Sharonov, visibility-meter IW GGO, visibility-polarization meter M-53. They were hand-held devices operating on the principle of comparing the brightness of the observed object with the patterns in the device or by extinguishing the brightness of the observed object. The photoelectric device was the visibility-meter M-37, it made it possible to make measurements during the day and at night. It consisted of a reflector with a powerful bulb. The strong beam of light sent by the reflector is weakened in the atmosphere, then goes to the receiving device, where the photocell converts it into an electrical signal measured with an appropriately scaled microammeter. The measurement of the upper limit of clouds was also carried out using various methods, using a pilot balloon (the time from the moment of take-off to the moment the balloon entered the clouds was measured), using the PI-45 reflector sending a strong beam of light vertically upwards. The M-105 optical sight was aimed at the spot of light on the cloud. In this case, the angle of its elevation was measured with an optical sight. The height of the clouds was found in the tables. All these measurement techniques were eliminated by modern measuring instruments introduced to the meteorological service in the sixties and subsequent decades. In the Polish Air Force aviation, the M-37, RDW-2 and RDW-3 photoelectric visibility meters were used, electronic devices for measuring the height of clouds, type IWO-1, IWO-1M (Izmieritel Wysoty Obłokow) and RWO-2 (Registrator Wysoty Obłakow), all production USSR.
Written by Marek Kaiper