B4-6 RELEASE AND RECORDER RECORD 
4. Entries on Recorder Record, Calibration Chart or WBAN-31A. 
4.1 Surface Observation at Release. Make acomplete surface observa- 
tion as close as possible to the time of the release and enter the data on 
WBAN-31A under the caption ''Surface Observation at Release". This 
observation may be taken just before the release provided that doing so 
does not delay the release and provided that not more than 10 minutes 
elapse between the beginning of the surface observation and the actual 
release, Whenever the surface observation is not taken within 10 minutes 
before the release time, it will be taken as soon as possible after the 
release, 
4.2 Time of Release. Enter the time of release tothe nearest minute, 
GMT, on the recorder record, calibration chart and the WBAN-31( ). 
4.3 Pressure. Enter the station pressure to hundredths of aninch and 
tenths of a millibar on WBAN-31A. However, stations equipped with a 
precision aneroid barometer calibrated in millibars will omit the entry 
in inches. (NOTE: All AF, N stations will read and record pressure in 
terms of millibars.). Use table B2-2 to correct the station pressure to 
the surface pressure. Enter the correction and the surface pressure to 
tenths of millibars on WBAN-31A. Surface pressure and surface altitude 
(gpm) refer to the value of the data at the following points listed in order 
of priority: 
a. The floor of the instrument shelter if within three meters of 
the actual height of the release point and the shelter is used 
in the measurement of the surface temperature and relative 
humidity. 
b. The intake of the official temperature measuring equipment 
(hygrothermometer, etc.) if within three meters of the actual 
height of the release point. 
c. The height of the release point, asestablished for the station. 
This height willbe considered to be four feet above the floor of 
the radiosonde balloon inflation shelter. 
4.4 Temperature. Whenever a telepsychrometer or hygrothermom- 
eter is available and operative, it will be used in accordance with in- 
structions in Federal Meteorological Handbook No. 1 (Surface Observa- 
tions) to obtain data for the raob surface observations. 
a. The telepsychrometer yields values for the dry-bulb and wet- 
bulb (via wet-bulb depression) temperatures. These values 
AGO FMH#3 
