B4-14 
RELEASE AND RECORDER RECORD 
SPETTTTTTTTTETTT TTT TTTTTTTTTTATTT TTT TTT TTT TTT 
Figure B4-5. Battery Failure. Levels cannot be selected after the bat- 
1-1-69 
tery begins to fail because the usual drift corrections are 
not applicable. During battery failure temperature and 
references drift independently of one another. 
At or between 10 and 20 mbabove the surface, when a surface 
based superadiabatic lapse rate is encountered. 
Between 400 and 500 mb, to provide a common level for 
WBAN-31A and 31Bwhenever a sounding extends toa pressure 
lower than 400 mb. Acommon level willbe provided similarly 
at or between 125 and 100 mb and 12.5 and 10.0 mb. 
At the base of a stratum within which icing occurs. The oc- 
currence of icing under favorable conditions of temperature 
and relative humidity is usually indicated by adecrease in the 
ascension rate of the raob balloon and aconsequent lengthen- 
ing of the contacts on the recorder record. Since a decrease in 
the ascension rate can be caused by turbulence as well as 
icing, the temperature and relative humidity willbe examined 
critically before assuming that the decrease is a result of 
icing. There should be a progressive increase inthe length of 
the contacts to support the assumption that the accretion of 
ice is increasing. This increase cannot usually be exhibited in 
less than four contacts. Moreover, the temperature should be 
FMH#3 
