B2-6 PREPARATIONS FOR SOUNDING 
Figure B2-1. AF Baseline-Check Box With Internal Power Supply 
4.1 Preparations for Baseline-Check. Make certain the contact armis 
off the commutator of the radiosonde. Open the box and position the 
radiosonde on the supports provided in the check box. Be certain that the 
airflow over the temperature and humidity elements is unrestricted. 
Connect, in correct order, the radiosonde test leads to the leads from 
the test switch. Turn on the radiosonde and close the door. 
5. The Baseline-Check. The baseline-check is required to establish 
a relationship between radiosonde transmitted values of temperature and 
humidity (recorded in terms of ordinate values by the radiosonde re- 
corder) and observed values of temperature and humidity (read from the 
psychrometer upon completion of the baseline- check). This temperature- 
humidity ordinate relationship is necessary to convert the ordinate 
values of temperature and humidity, recorded during the sounding, to 
temperature in degrees Celsius and relative humidity in percent. The 
importance of obtaining accurate values in the baseline-check cannot be 
over-emphasized. 
5.1 Adjustment of Equipment. The following adjustments will be made 
to the equipment before making the baseline-check. The radiosonde 
should be conditioned in the closed box before starting the baseline- 
check recordings. The amount of time required to produce stable tem- 
perature and humidity conditions will depend upon the climatic condi- 
tions occurring at the station. The blower should be operated only long 
enough to produce stable temperature and humidity conditions. If the 
13 L398) FMH#3 
