Chapter 4 — TEMPERATURE, HUMIDITY, AND PRECIPITATION 



measurements. If the ground is covered by ice 

 beneath the snow, the observer must cut through 

 the Ice, measure the thickness, and add it to the 

 depth of the snow above the ice. The unmelted 

 depth of solid forms that have fallen during the 

 6 hours ending with the observations is ex- 

 pressed in inches to the nearest tenth of an 

 inch, but the total depth of solid forms on 

 the ground at the time of observation is ex- 

 pressed to the nearest inch. 



OBSERVATIONS AND FORMS 



A varied assortment of forms are used to 

 record temperature, humidity, and precipitation 

 observations. Some have already been discussed, 

 such as the MF1-10 and NWSC Form 3140/8. 



The AN/GMQ-29 records rainfall and winds 

 while the AN/GMQ-14( ) records temperature, 

 dew point, and rainfall on recorder rolls. These 

 forms and record rolls and their entries are 

 discussed in the following paragraphs. 



MF1-10 and NWSC Form 3140/8 Entries 



Entries of temperature, dew point, maximum 

 and minimum temperature, and climatic in- 

 formation are made in accordance with the 

 criteria set forth in the following paragraphs. 

 Again, when this chapter does not cover an as- 

 pect of the problem at hand, consult FMH No. 1, 

 Surface Observations. 



TEMPERATURE (COL. 7). — Temperature Is 

 entered to the nearest whole degree Fahrenheit, 

 prefixing a minus sign to a subzero tempera- 

 ture. 



DEW POINT (COL.8). — Entered the same 

 as temperature unless the dry-bulb tempera- 

 ture is -35° F or below. Then assume the 

 dew point, with respect to ice, to be the same 

 as the dry-bulb. The water equivalent of this 

 value Is computed and then entered in paren- 

 theses. 



PRECIPITATION (COL. 44). — Measurements 

 of all forms . of precipitation are expressed In 

 terms of vertical depth of water accumulated 

 within a specified time on a horizontal surface. 



Enter total precipitation (water equivalent) 

 In inches and hundredths. Also, when: 



1. No 6-hour precipitation occurs, enter "0". 



2. A trace, but less than 0.005 inch falls, 

 enter "T". 



3. No 6-hour precipitation up to the actual 

 observation time, but precipitation was observed 

 prior to coding of the observation, enter "T" 

 even though the amount may be measurable. 



If the water equivalent of solid precipita- 

 tion cannot be measured by melting or weighing 

 of the sample, enter the estimated water equiva- 

 lent on the ba3is of the ratio method. For fur- 

 ther details, see FMH No. 1. 



SNOWFALL (COL.45). — In this column, enter 

 the maximum unmelted depth, in Inches and 

 tenths, of solid precipitation that has fallen 

 during the 6 hours ending with the observation. 



Additional entry instructions are as follows: 



1. No 6-hour snowfall, enter "0". 



2. A trace but less than 0.05 Inch, enter 

 "T" and in block 90, when snowfall melted 

 as it fell, enter also "T — Melted as it fell." 



3. If several occurrences of solid precipi- 

 tation oocur in the period, such as snow showers, 

 and each fall melts either completely or par- 

 tially before the next occurs, enter the total 

 of the meximum depths accumulated by each 

 fall. 



4. As a prefix to estimated amounts, enter 

 "E"; in block 90, enter "E — Estimated due 

 to melting." 



5. Enter an asterisk (*) as a prefix to HAIL 

 amounts, and in block 90, enter "*HAIL," un- 

 less other solid forms of precipitation occurred 

 during the period. 



Additional information is contained In FMH 

 No. 1. 



SNOW DEPTH (COL.46). — In this column, 

 to the nearest Inch, enter In the 6-hourly spaces 

 the depth of solid precipitation and ice on the 

 ground at each 6-hourly observation. Additional 

 entry instructions are contained in FMH-1. 



MAXIMUM TEMPERATURE (COL.47). — En- 

 ter the maximum temperature in whole degrees 

 Fahrenheit that has occurred in the 6 hours 

 prior to each 6-hourly observation and between 

 midnight and the first 6-hourly observation and 

 between the last 6-hourly observation and mid- 

 night, on the line captioned 1,2,3, and 4 and 

 MID TO and MID, respectively. 



MINIMUM TEMPERATURE (COL.48). — En- 

 tered the same as column 47. 



53 



