AEROGRAPHER'S MATE 3 & 2 



the appropriate color of balloon; use red balloons 

 for thin clouds and black balloons under other 

 conditions. 



The Universal Balloon Balance (ML- 

 575/UM) is used to inflate the 10-gram ceiling 

 balloon for use. The nozzle lift should be 

 so adjusted that it weighs EXACTLY 43 grams 

 when inflating the balloon with helium. 



Since the ceiling balloon is not used to 

 reach altitudes much beyond 2,500 feet, the 

 rapidity of inflation is not highly important; 

 however, an attempt should be made to inflate 

 it in about 3/4 to 1 minute. 



Ceiling balloons should be stored in a 

 dry, warm environment. The temperature 

 should be as high as possible, but should not 

 exceed 120°F. When the balloons have been ex- 

 posed to temperatures below freezing, they 

 should be stored at a temperature of 65°F 

 or higher for at least 12 hours prior to removal 

 from their container. They should not be placed 

 immediately adjacent to large electric gen- 

 erators or motors. Motors and generators emit 

 ozone, which is detrimental to neoprene. 

 Balloons lose their strength with age; there- 

 fore, they should be used in the order of 

 their production dates to avoid excessive aging. 

 Ceiling balloons need not be conditioned prior 

 to use. 



When using a ceiling balloon, note the 

 length of time (use a stop watch or any watch 

 having a second hand) that elapses between 

 the release of the balloon and entry into the 

 base of the layer. The point of entry is con- 

 sidered as midway between the time the balloon 

 first begins to fade and the time of complete 

 disappearance. Determine the height above the 

 surface corresponding to the nearest 5 seconds 

 of elapsed ascent time from tables found in 

 FMH-1. The accuracy of this height will be 



affected when the balloon does not enter a 

 representative portion of the cloud base; when 

 it is used at night with a light; or if obtained 

 during the occurrence of hail, ice pellets, 

 freezing rain, or moderate to heavy rain or 

 enow. 



VISIBILITY MEASURING 

 EQUIPMENT 



The Transmissometer AN/GMQ-10 is the 

 only type of visibility measuring equipment in 



general use throughout the Navy. It provides 

 data through two separate readout components, 

 the Indicator-Recorder, Transmissometer 

 1D820/GMQ-10C (Indicator, Transmissometer 

 1D353/GMQ-10B) for visibility Indications, and 

 Converter-Indicator Group OA-7900A/GMQ-10 

 for runway visibility indications. 



TRANSMISSOMETER AN/GMQ-10( ) 



Transmissometer Set AN/GMQ-10 ( ) is an 

 electronic instrument which provides a con- 

 tinuous record of the atmospheric transmission 

 between two fixed points. The horizontal visi- 

 bility may be determined by the application 

 of conversions to these measurements. The 

 operation of the transmissometer is nearly 

 automatic, requiring only occasional attention 

 of an operator to make minor adjustments. 

 It uses 11 5- volt, 60-hertz alternating current 

 for its source of power. 



The transmissometer is designed to pro- 

 vide visibilities in the range of 0.05 to 2 miles 

 in the daytime and 0.1 to 2 miles in the night- 

 time when a 500-foot baseline is used. For 

 visibilities greater than these, the indication 

 is generally good, but the accuracy of the 

 visibility measurements decreases with in- 

 creasing visibility. 



Components 



The transmissometer set may be con- 

 veniently divided into the following systems. 

 Each of these systems is constructed as a 

 separate unit. 



The PROJECTOR consists of an alignment 

 system and a sealed- reflector lamp operated 

 at a constant intensity. The projector directs 

 a light beam of constant intensity toward the 

 receiver. The amount of light reaching the 

 receiver varies with the density of the fog 

 or haze in the path between these two instru- 

 ments. (See fig. 5-14.) 



The PROJECTOR POWER SUPPLY furnishes 

 power at a regulated voltage to the projector 

 for the lamp filament. Facilities are provided 

 for making checks by turning the power off 

 automatically at fixed intervals and off manually 

 from the indicator. 



The RECEIVER consists of a telescope 

 to collect light from the projector, and a 



92 



