BALLOON INFLATION AND ASSEMBLY OF TRAIN B3-3 
f. If the outside temperature is 40°F or above, the balloon is 
ready for inflation. If, however, the outside temperature is 
below 40°F, the balloon should be allowed to dry before in- 
flating. Hang the balloon by the neck to facilitate drying. 
1.5 Heat Conditioning Method. In an emergency, ifneither the electric 
nor hot water conditioning method can be used, neoprene balloons may 
be conditioned by removing them from their polyethylene bag, and then 
placing them over a heater, radiator, orelectric lamp, care being taken 
to insure uniform heating and to shield the balloon from direct contact 
with the heat sources. A conditioning period of 12 hours should be used 
with temperatures near 65°C and relative humidity near 100 percent. 
The length of the conditioning period should be decreased as the temper- 
ature is increased. The balloons should not be exposed to temperatures 
in excess of 100°C. 
2. Inflation Lift Requirements, The amount of helium, hydrogen, or 
natural gas most favorable for producing optimum performance should 
be ascertained before actual inflation of the balloon. Optimum perform- 
ance is usually defined as the highest possible bursting altitude, with an 
average ascent rate favorable for obtaining winds-aloft data. Lift is de- 
fined as follows: 
a. Free Lift - Free lift is the number of grams of lift that are 
available over and above that required by aballoon to support 
the weight of a complete radiosonde train. 
b. Nozzle Lift - Nozzle lift is free liftplus the grams of lift re- 
quired by a balloon to support the weight of a complete radio- 
sonde train. 
ec. Gross Lift - Gross lift isnozzle lift plus the grams of lift re- 
quired to support the weight of the balloon. 
2.1 Performance of the Balloon. The performance ofa balloon (burst- 
ing altitude and ascent rate) is affected by the free lift, thickness of the 
neoprene film, current air mass and weather conditions, and the size and 
shape of the balloon envelope. Since most ofthese factors cannot be con- 
trolled, the free lift to produce optimum performance for any given 
sounding can best be determined by experience. The following paragraphs 
are included as a guide. 
a. For fair-weather conditions, free lift ranging from 1000 to 
1400 grams for 600 to 1200 gram balloons (including severe 
weather balloons) and 800 to 1000 grams free lift for 300 gram 
balloons, will normally produce optimum performance. 
= 1L= 69) FMH#3 
