2-41. From the arrangement below, select the 2-47. 

 correct sequence of steps you perform when 

 operating the Hand Electric Psychrometer 

 ML-450A/UM at temperatures above 50°. 



A. Place psychrometer in operating 

 position 



B. Saturate wet-bulb wick 



C. Turn switch knob counterclockwise 



D. Evaluate readings 



E. Expose psychrometer to free air for 

 at least 5 minutes 



F. Take readings 



G. Turn switch knob clockwise 



1. A, B, C, E, F, G, D 



2. B, A, G, E, F, C, D 2-48. 



3. E, B, A, G, F, C, D 



4. G, B, A, E, F, C, D 



2-42. When full, the tube of the 4-inch rain 

 gage holds how many inches of rainfall? 



1. One inch 



2. Two inches 



3. Three inches 2-49. 



4 . Four inches 



2-43. The unmelted depth of solid precipitation 

 that has fallen during the past six hours 

 is entered on MF1-10 to the nearest 



1. 0.01 in 



2. 0.10 in 



3. 0.50 in 



4. 1.00 in 



2-44. Even though the precipitation amount to 

 be entered in column 44 of an MF1-10B 

 form is the total precipitation for the 2-50. 

 indicated period to 0.01 of an inch, what 

 is entered if only a trace of precipita- 

 tion occurs? 



1. T 



2. Trace 



3. 0.005 



4. 0.05 



2-45. If a thunderstorm has passed over a 



station and the last thunder was heard 2-51. 

 at 1552 LST, the time of thunderstorm 

 ending is listed in what column and as 

 what time on the MF1-10 form? 



1. 83 as 1600 



2. 83 as 1615 



3. 84 as 1552 



4. 84 as 1607 



2-46. The 6-hourly time-check mark must be 



accompanied by the observer's initials on 

 the 



1. wind recorder chart 



2. microbarograph chart 



3. transmissometer record 



4. temperature/dewpoint chart 



The operation of the standard air ther- 

 mometer depends upon the 



1. similarity of the coefficients of 

 expansion of glass and air 



2. similarity of the coefficients of 

 expansion of glass and alcohol or 

 mercury 



3. difference between the coefficients 

 of expansion of air and alcohol or 

 mercury 



4. difference between the coefficients 

 of expansion of glass and mercury or 

 alcohol 



What is the range of the standard air 

 thermometer used by the Naval Weather 

 Service? 



1. 



0° 



F 



to 



+140° 



F 



2. 



+20° 



F 



to 



+120° 



F 



3. 



-10° 



F 



to 



+110° 



F 



4. 



-20° 



F 



to 



+120° 



F 



The metal back of the standard air ther- 

 mometer should be removed and cleaned at 

 what intervals and with what cleaning 

 agent? 



1. At least every three months with 

 ammonia 



2. 10 to 15 minutes prior to each reading 

 with a soft cloth dipped in light oil 



3. As necessary with a solution of bicar- 

 bonate of soda 



4. As required by the preventive main- 

 tenance schedule with steel wool 



If the mercury column of a standard air 

 thermometer should become separated, the 

 final method to use to reunite it should 

 be by 



1. applying heat to the bulb by placing 

 it near a light bulb 



2. tapping the bulb 



3. slinging the thermometer 



4. heating the bulb over an open flame 



In making a humidity check with a sling 

 psychrometer, the operator must be care- 

 ful to avoid all but which of the 

 following? 



1. Direct sun rays 



2. Any trace of wind 



3. Touching the bulb or stem 



4. Bringing the psychrometer to a 

 sudden stop 



13 



