In the years before weather satellites and sophisticated electronic sensors became common, meteorologists often used a pilot balloon, or pibal, to determine wind speed and direction at different altitudes. While technology has advanced, the trusty pibal is still a helpful tool for many applications. Let’s take a look at the history of these balloons and their uses.
What Is A Pibal?
As stated above, pibals are lightweight balloons that measure wind speed and direction at various altitudes. Balloons typically are filled with helium, although early pibals often used hydrogen, and released into the atmosphere.
As the balloon rises, an observer, often using a theodolite, tracks its movement to determine how the winds behave above the ground. The balloon’s azimuth and elevation angles are tracked at set intervals.
The azimuth angle shows the compass direction in which the balloon has moved, while the elevation angle shows how high it appears above the horizon. By comparing these angle readings over time—and accounting for the balloon’s expected rate of ascent—the observer can calculate wind speed and direction at different altitudes.
Similar to pilot balloons, there are also devices known as ceiling balloons. While pilot balloons measure wind speed and direction, a ceiling balloon measures cloud-base height. This is crucial for aviation as a low cloud base can reduce visibility and affect takeoffs, landings, and flight routes.
Cloud-base measurements also help meteorologists identify changing weather conditions and monitor the development of fog and storms. This data also can help determine whether conditions are suitable for aircraft, drone, and pilot balloon operations, as well as helping scientists prepare more accurate forecasts.
A Brief History of Pilot Balloon Use
In the mid-18th century, scientists began observing upper air conditions using kites that were outfitted with a thermometer. Hot air balloons, utilizing hydrogen, were invented in the 1780s, and this allowed the scientists to ascend into the atmosphere armed with thermometers, barometers, and other related gear to study the air at higher elevations.
While these investigations yielded important information, they could be quite dangerous for the participants, and several fatalities occurred. In the 1860s, however, scientists developed a device known as a meteorograph. This device could record a variety of weather conditions, including air pressure, humidity, and temperature.
The meteorograph could be placed in an unmanned balloon, which could ascend to much higher altitudes. Once the balloon burst, the meteorograph could be recovered in the balloon debris, and the results could be studied.
Pilot Balloons In A Modern World
With the advancement of technology, it may surprise you to learn that pilot balloons and ceiling balloons are still in use today. After all, satellites, weather radar, radiosondes, and other electronic systems now provide enormous amounts of atmospheric data.
However, pilot balloons continue to be useful in applications that require a relatively simple and portable way to observe upper-air winds. A pibal system can be transported into the field and operated without permanent radar installations or other large pieces of infrastructure.
For instance, military meteorological teams may use pilot balloons to evaluate wind conditions during field operations. Knowing how winds change with altitude can support aviation activities, parachute operations, artillery calculations, smoke-drift predictions, and other missions affected by air movement. Portable equipment can be particularly valuable when personnel must collect local wind data far from an established weather station.
Atmospheric researchers, field meteorologists, and remote weather stations may also use PIBAL observations to study local wind patterns or collect data in places where more sophisticated equipment is unavailable or impractical. Because the balloon moves with the surrounding air, tracking its path can help reveal wind speed and direction at several levels above the ground.
Aviation, aerospace, rocket, drone, and balloon-launch teams may need upper-air wind information when planning operations. Winds at the surface can differ significantly from those found hundreds or thousands of feet overhead. A pilot balloon observation can help these teams better understand the conditions a vehicle may encounter after takeoff or launch.
Pilot balloons can also serve educational and training purposes. Universities, meteorology programs, and technical training organizations may use them to demonstrate upper-air observation methods and help students understand concepts such as balloon ascent rate, azimuth, elevation, and wind profiling.
While a pibal system does not replace every modern atmospheric instrument, it remains a practical option when portability, straightforward operation, and localized wind observations are important. Its continued usefulness comes from the simple principle behind it: release a visible balloon, carefully track its changing position, and use those observations to determine how the winds are moving above the ground.
Warren-Knight: Our Weather Balloons & Meteorological Instruments
At Warren-Knight, we offer both a ceiling balloon and two pilot balloon options. Our WK-22-3010 Ceiling Balloon can be used to ascertain cloud height by timing the ascent of the balloon. Both our WK-22-3030 Pilot Balloon (30 grams) and the WK-22-3100 Pilot Balloon (100 grams) are to be used with a theodolite to determine wind speed and direction.
Additionally, we offer the WK-20-8403 Pilot Balloon Theodolite, which can be used with our weather balloons or to measure the elevation and azimuth of aircraft, ships, or other moving objects at distances of 20,000 meters or more, depending on visibility.
Our WK-20-9100 Electronic Meteorological Theodolite also can be well-suited to pilot balloon work and provides fast, accurate angle measurement with minimal reading errors. Its 21x main tracking telescope and 4x wide-angle finder help operators locate and follow a moving balloon, while the LCD display and RS-232 connection allow horizontal and vertical angle readings to be viewed electronically or transferred to a computer for storage.
We recommend pairing this theodolite with our WK-22-4850 Pibal Timer. A pibal timer helps observers record a balloon’s azimuth and elevation at precise intervals. Because the balloon rises at an established rate, matching each angle reading to the correct elapsed time helps determine the balloon’s altitude and calculate wind speed and direction at different levels.
Warren-Knight: Quality Precision Instruments Since 1908
At Warren-Knight, we have been a top producer of precision instruments for more than a century. In addition to meteorological instruments, we design and produce navigation instruments, optical instruments, metrology equipment, levelling instruments, and surveying equipment. We also offer instrument calibration services and repair services, including NIST traceable calibration.
Whether you need a pilot balloon, meteorological theodolites, or another device, we can provide instruments that align with all of your specifications. Contact us at any time to discuss any of our products. We also offer rental services for many devices, including theodolites, total stations, field computers, transits, clinometers, and much more.