Weather Brief Figure 6-2.  Simple wind observations. Figure 6-3.  Checking wind velocity with a handheld wind meter. Perhaps the cheapest yet most valuable launch site weather  aid is the pibal or pilot balloon, a 10–14" helium-filled  balloon released at the launch site for visual weather cues  and forecast confirmation. Some pibal actions clearly mean  cancel the flight: rolling along the ground, not clearing  obstacles, climbing then diving, or dramatic speed/direction  changes (which indicate wind shears). To read and confirm  winds at different altitudes, release several pibals at 10–20  second intervals. Fill the first with 100 percent helium, the  second with mostly helium and a breath of air from your  mouth, and the third with helium and two breaths. This  creates different rates of ascent which helps gain a better  perspective of the low level winds. Every pilot benefits from  having pibals in their vehicle and using them before launch.  Appendix D lists various rates of climb for different sizes  of pibals; using this knowledge, the pilot can determine the  altitudes at which the winds change.  The balloon can sometimes provide valuable weather  information provided the pilot knows what to look for. Fabrics  on a laid-out envelope begin rippling around eight miles per  hour (mph), while 10–12 mph sends small bubbles of air past  a closed throat and up along the load tapes. Such information,  perhaps unavailable or inaccurate elsewhere, can prove  invaluable, especially during the initial phase of flight. Despite using the most current and complete electronic  weather data available to consider before driving out for  the flight, each pilot must never lose sight of the fact that  hot air balloons are visual flight rules (VFR) aircraft. Many  pilots lose all access to unlimited or even selected electronic  weather information en route to or at the launch site. Unless  the launch site is a reporting station for any weather service,  a pilot is required to visually interpret and evaluate weather  data specific to the launch site. Local surface conditions— particularly winds below 500'–800'—show the greatest  variability of both speed and direction. These winds are  perhaps of greatest importance in determining the conditions  and risks for launch and landing. A number of simple  observations enable the balloon pilot to gather this data at the  launch site, as well as during the flight.  [Figure 6-2] All electronic sites and briefings represent the starting point  for how weather affects the flight. A balloon pilot should  not make the mistake of gathering weather data, getting  a forecast, deciding to fly, and then paying less attention  to actual weather cues. Weather monitoring is an ongoing  process that starts on the drive to the launch field and  continues until the balloon is packed after landing. Continue  gathering weather data for the flight until safely back on the  ground. Some pilots choose to rely on a portable weather station  or handheld wind meter to monitor local conditions at the  launch site. Cost, size, portability, and features vary among  brands, but each can provide useful information on wind  speed/direction, maximum gusts, and other weather data.  These can range from a small $100 handheld wind meter  to a $500 weather station with 15" mast and dashboard data  display.  [Figure 6-3] Each pilot must sharpen his or her ability to read and interpret  local surface conditions for one primary reason: up to 1  hour may elapse between gathering weather data online and  laying out at the launch site. Weather patterns can change  in far less time than this, and local conditions can change  almost instantly. As previously discussed, a weather brief must be obtained  prior to flight; as a procedural matter, the information from  the briefing sets the parameters for the flight (launch site,  flight track, and potential landing areas).  Smoke begins drifting off of vertical at 2–3 mph Most deciduous tree leaves begin rustling above 4–5 mph  (except aspens, birch, and other broadleaf trees, which respond at lower wind speeds) Twigs sway and flags extend around 7–8 mph Dust and paper kick up off the ground above 12 mph Wires and ropes whistle above 20 mph Simple Wind Observations 6-3