Chapter 4 -TEMPERATURE, HUMIDITY, AND PRECIPITATION 



CA* 



209.83 

 Figure 4-3. — Standard instrument shelter. (A) 

 Construction of support. (B) Instrument arrange- 

 ment inside the shelter. 



SLING 



The sling psychrometer, is shown in figure 

 4-5. The sling consists of a wooden grip with 

 a swivel head and harness-type snap or spring 

 clip for attaching to the top hole of the psy- 

 chrometer frame. 



When not in use, the sling psychrometer 

 should be hung on a suitable hook. 



Handle the sling psychrometer carefully at 

 all times. The thermometers are easily broken 

 through careless handling, dropping, or strik- 

 ing some object while being whirled. 



For a check on humidity, take it to a clear 

 and open place, preferably exposed to the wind. 

 Never touch the bulb or stem in handling or 

 expose It to the direct rays of the sun while 

 making an observation. The bulb of the wet- 

 bulb thermometer, which is covered with a 



209.392 

 Figure 4-4. — Shelter used with AN/GM3-14( ). 



wick, is moistened with clean water at the time 

 an observation is made. Stand in a clear shady 

 place facing into the wind, and hold the psy- 

 chrometer as far in front of the body as pos- 

 sible. Rotate the psychrometer with the wrist. 

 Bring the psychrometer to a stop without any 

 sharp jar and bring to eye level. Then read 

 both thermometers to the nearest tenth of a 

 degree, reading the WET-BULB thermometer 

 FIRST. The whirling is repeated, and other 

 readings are made until two successive wet- 

 bulb readings are the same. Amplifying in- 

 formation is contained in FMH-1. 



ROTOR 



The rotor psychrometer illustrated in fig- 

 ure 4-6 is a psychrometer element secured 



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