To inflate a balloon, hold the inflation hose 2 to 3 inches from the connection to the balloon nozzle and allow the gas to flow into the balloon until the balloon just supports the weight of the inflation nozzle assembly (to achieve neutral buoyancy). It is a good idea to shut off  the  valve  when  the  balloon  is  about  half-full  and listen for any leaking air from holes that may be in the balloon.  Finally,  shut  off  the  gas  flow  and  tie  off  the balloon. If  balloon  inflation  weights  are  not  available, balloons may be inflated using only the regulator. You may inflate the balloons with the required amount of gas by using the inner (cubic feet) scale of the high-pressure dial. To achieve approximately 700 grams of free lift, a 100-gram  balloon  will  take  about  40  cubic  feet  of helium. To achieve 900 grams of free lift, a 300-gram balloon will need about 70 cubic feet of helium. In any case, the balloon should produce a fairly strong pull or tug on the nozzle and hose. A D J U S T M E N T S    T O    I N F L A T I O N .— Ascension rates should be calculated for all soundings. Because of environmental conditions, free lift weight is adjusted to better target the 900 to 1,000 feet per minute desired  ascension  rate.  During  precipitation  or  icing, you  must  increase  the  free  lift  to  compensate  for  the additional weight of water, snow, or ice on the balloon. For  example,  during  light  rain  or  drizzle,  you  must increase free lift (weight of inflation nozzle assembly) by 100 grams or increase the helium in the balloon by 3 to  4  cubic  feet.  When  light  to  moderate  icing  or moderate to heavy precipitation is anticipated, increase the free lift by 200 to 300 grams or increase the helium by 7 to 11 cubic feet. However, increasing the free lift by more than 300 grams during severe icing conditions may  slow  the  ascent  rate  because  of  the  increased surface area on which ice may collect. Tying the Balloon After inflation, it is imperative that the balloon neck be tied properly to prevent leakage of gas and to allow for attachment of the instrument. Most balloons can be sealed by using a single loop over the unwinder gripper and a plastic tie. If no plastic ties are available, use a 3- to 4-foot length of cotton textile tape (balloon tape) or a medium thickness cotton twine. Fold the twine in half to obtain a double thickness. While the balloon is still on the inflation nozzle, tie a tight square knot around the balloon neck about 1 1/2 to 2 inches below the body of the balloon. Remove the balloon from the nozzle and loop the excess balloon neck up and over the first knot by about an inch. Then, wrap the loop tightly with the remaining cord ends, and tie it securely with a second square knot. The loop in the balloon neck must be large enough  to  insert  the  gripper  of  the  balloon  winder through the loop (fig. 1-6). The remaining excess cord is  used  to  handle  the  balloon  before  release.  The balloon cord should be attached to the unwinder gripper with a double square knot prior to release. Tying the cord to the gripper will help prevent the gripper from chaffing the balloon loop during gusty wind conditions. Allow  no  more  than  6  to  8  feet  of  train  from  the unwinder. Use of Parachutes Parachutes are neither required nor recommended for use during an MRS sounding. The 250-gram RS-80 series  radiosonde  instrument,  even  when  in  free-fall after balloon burst, has sufficient drag that even a direct strike to a person on the ground will cause no serious injury.  However,  the  National  Weather  Service  does require their use. If a parachute is elected for use at land stations,  the  parachute  is  tied  to  the  balloon,  and  the radiosonde  is  affixed  to  the  bottom  of  the  parachute. Use of the 6-foot paper parachute or the 6-foot cloth parachute requires that an extra 100 grams be added to the nozzle weight during Inflation to maintain proper free  lift.  Meteorological  parachutes  are  never  used  at sea. Use of Balloon Shrouds A balloon shroud is recommended for use to protect and securely hold or move the balloon and radiosonde prior  to  launch  during  windy  conditions.  The  fabric balloon shroud may be used to hold balloons up to 7 1/2 feet  in  diameter.  When  moving  a  balloon,  use  the handles at the comers of the shroud. The cloth bands at the  apex  of  the  shroud  may  be  used  to  attach  an anchoring line, which is used to pull the shroud off the balloon  as  the  handles  are  released  during  launch. Balloon shrouds must be hung to dry if used during rain, and  must  contain  an  antistatic  electricity  treatment  if used with hydrogen or natural-gas-filled balloons. Q8. Q9. Q10. Q11. REVIEW   QUESTIONS What is the purpose of the GPS antenna? What  are  the  two  most  widely  used  gases  for meteorological   balloons? What   are   the   two   most   commonly   used meteorological balloons sizes? What is the only part of the balloon that should be  touched? 1-8