Chapter 5 — CLOUDS AND VISIBILITY 



RIGHT BLADE 

 STOP 



PEED ROLL 

 TOP PLATE 



TAKE UP ROLL 



VERNIER 

 CONTROL LEVER 



HELIX TIMING BELT 

 DRIVE ASSEMBLY 



LUCITE WINDOW 



BLADE 

 (ENDLESS LOOP ELECTRODE) 



TOP PLATE 

 (CRADLE) 



CAM LOCK 



RIGHT SCREW 

 COVER 



209.386 

 Figure 5-13. — Cloud height recorder RO-121/GMQ-13 with door open and showing paper installation. 



are to be made regularly by station electronics 

 personnel. The check should be made on or about 

 the same day each week in order to realize the 

 greatest benefit. It is the responsibility of the 

 meteorologist in charge to see that these checks 

 are made and to take necessary action to keep 

 the equipment in operation. Cleanliness of the 

 recorder and indicator is maintained by the 

 Aerographer's Mate operators. 



RECORDER.— Check inside recorder cover 

 for dust and clean if necessary. This condition 

 will vary depending on periods of idleness. 

 Clean the plastic portion of the recorder cover 

 using a soft cloth to prevent scratching. 



INDICATOR. — Clean the air intake below the 

 front door by removing the mesh cover and 

 blowing or brushing dirt from the mesh. The 

 cover may be removed by prying it from the 

 cabinet with a screwdriver. Clean the plastic 



cover with a small piece of cloth moistened 

 with water. Because the cover is plastic, it 

 must be wiped lightly to avoid scratching. 



BALLOON DETERMINATIONS 



The standard balloon specifically designed 

 to measure the height of clouds (ceiling) is 

 the 10-gram, black or dark blue ceiling balloon. 

 The ceiling balloon is normally used to determine 

 the height of the ceiling when the broken 

 or overcast layer of clouds is 2,500 feet or 

 less. Sometimes, it is desirable to obtain 

 a more rapid ascent than can be obtained with 

 a 10-gram balloon; for instance, when taking 

 a balloon ceiling under adverse wind conditions. 

 Under adverse conditions, or when it is neces- 

 sary to save time, it is permissible to use 

 either a 80-gram balloon or a 100-gram balloon, 

 depending on the desired ascension rate. When 

 using either of these two balloons, choose 



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