Within Wind Data
Why balloons can change course overhead
Radiosonde profiles can show why a balloon seems to curve, slow or change direction as it climbs through different wind layers.
On this page
- What radiosondes measure during ascent
- How wind layers change a visible track
- Limits when height and path are uncertain
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Introduction
When a balloon-like object reported as a UFO appears to curve, slow down, speed up, or reverse direction, one of the most useful pieces of evidence is an upper-air sounding. A sounding is a vertical profile of the atmosphere collected by a radiosonde carried beneath a weather balloon. Rather than describing only the wind at ground level, it reveals how wind speed and direction change with height. Because a drifting object may pass through several distinct wind layers during ascent, its visible track can differ dramatically from the breeze experienced by witnesses on the ground. In many investigations of unidentified flying objects, soundings provide a direct way to test whether apparently unusual motion is consistent with an ordinary balloon entering different air currents. [noaa.gov]noaa.govNational Oceanic and Atmospheric…16 Sept 2025 — The radiosonde is a small instrument package that is suspended below balloon filled wi… [MeteoSwiss]meteoswiss.admin.chMeteo Swiss Weather balloonMeteoSwissWeather balloon - MeteoSwissRadiosondes measure temperature and humidity. Their precise position is recorded using a GPS system…
Why balloons can change course overhead
A free-floating balloon does not move through a single, uniform air mass. As it climbs, it encounters layers of atmosphere that may be travelling in different directions and at different speeds. Radiosonde soundings were developed specifically to measure these changes.
Meteorological agencies derive upper-level winds by tracking the radiosonde’s position with GPS or other tracking methods as the balloon ascends. The resulting profile shows wind direction and speed at many altitudes rather than a single surface reading. [National Weather Service]weather.govNational Weather ServiceUpper Air10 Dec 2024 — Winds are also derived by using a GPS system that tracks the balloon location to calculate… MeteoSwiss For a witness on the ground [meteoswiss.admin.ch]meteoswiss.admin.chMeteo Swiss Weather balloonMeteoSwissWeather balloon - MeteoSwissRadiosondes measure temperature and humidity. Their precise position is recorded using a GPS system…, several effects can result:
- A balloon may drift eastward at low altitude, then curve north-east after entering a new wind layer.
- Apparently steady motion may become much faster if the balloon reaches stronger winds aloft.
- A balloon can seem to pause or slow relative to the background if it enters a layer with weaker winds.
- A long, smooth arc across the sky may be produced by gradual wind veering with height rather than by any active manoeuvre. [webmet.com]webmet.com9.1.2 Radiosonde Sounding SystemWebMETBy measuring the position of the balloon with respect to time and altitude, wind vectors can be computed that represent the layer-a…
These behaviours are often surprising because observers naturally compare the object’s movement with the wind they can feel at the surface. A sounding tests whether the atmosphere above them was behaving differently.
What radiosondes measure during ascent
A radiosonde records pressure, temperature and humidity directly. Wind measurements are obtained by tracking the instrument’s changing position as it rises through the atmosphere. Modern systems use GPS-derived positions to calculate wind speed and direction at successive heights. [National Weather Service]weather.govNational Weather ServiceUpper Air10 Dec 2024 — Winds are also derived by using a GPS system that tracks the balloon location to calculate… [3noaa.gov]noaa.govNational Oceanic and Atmospheric…16 Sept 2025 — The radiosonde is a small instrument package that is suspended below balloon filled wi… MeteoSwiss The value for UFO investigations lies in the vertical structure of the data. A typical sounding may extend from near the surface to around 30 [meteoswiss.admin.ch]meteoswiss.admin.chMeteo Swiss Weather balloonMeteoSwissWeather balloon - MeteoSwissRadiosondes measure temperature and humidity. Their precise position is recorded using a GPS system… kilometres altitude, revealing numerous layers with distinct wind characteristics. The World Meteorological Organization notes that a global network of roughly 1,300 upper-air stations launches radiosondes to measure pressure, temperature, humidity and wind velocity through much of the atmosphere. [World Meteorological Organization]seedmech.comWORLD METEOROLOGICAL ORGANIZATIONThe purpose of the Guide to Meteorological Instruments and Methods of Observation is to support these ac…
In practical terms, investigators can compare a reported object’s apparent behaviour against the sounding profile:
- Did the object begin changing direction at a height where the sounding shows a wind shift?
- Did acceleration coincide with stronger winds aloft? [ncei.noaa.gov]ncei.noaa.govof Winds Aloft - WBAN 120Provisions exist on these forms for listing wind direction and speed at heights up to 42,000 meters. The first p…
- Does the reported track match the sequence of wind vectors measured during the launch?
When those features align, a drifting-balloon explanation gains substantial support.
How wind layers change a visible track
The most important insight from a sounding is that wind does not simply increase with height in a straight-line fashion. Direction can rotate significantly between layers, and speed can vary from calm conditions to very strong upper-level flow.
Weather-service documentation notes that radiosondes entering jet-stream regions can experience extremely high drift speeds. A balloon ascending through such an environment may appear to observers to suddenly accelerate despite having no propulsion of its own. [National Weather Service]weather.govNational Weather ServiceUpper Air10 Dec 2024 — Winds are also derived by using a GPS system that tracks the balloon location to calculate…
Consider a simplified example:
- A balloon launches into a low-level south-westerly flow.
- At 1–2 km altitude it enters a westerly layer.
- Higher still, it encounters north-westerly winds moving much faster.
To a witness, the object may first travel north-east, then gradually bend eastward, and later sweep towards the south-east at greater speed. Without upper-air data, such behaviour may seem erratic. With a sounding profile, it can be reconstructed as the expected response of a passive object moving through changing winds. [webmet.com]webmet.com9.1.2 Radiosonde Sounding SystemWebMETBy measuring the position of the balloon with respect to time and altitude, wind vectors can be computed that represent the layer-a…
This is one reason balloon reports sometimes generate descriptions of “course corrections” even when no powered flight is involved.
A sounding is itself evidence of balloon drift
An often-overlooked point is that the radiosonde balloon used to create the sounding also demonstrates how strongly balloons can drift. Weather balloons do not rise vertically above their launch site. They are carried horizontally by winds throughout their ascent.
National Weather Service material notes that a radiosonde can drift more than 200 kilometres from its release point during a flight and can encounter very strong upper-level winds. Academic studies of radiosonde trajectories likewise show that drift distance generally increases with altitude and varies with season and location. [ROSA P]rosap.ntl.bts.govROSA PHigh-Altitude Wind Prediction and Measurement…by RL Walterscheid · 2009 · Cited by 10 — It takes an hour or more for balloons to… [National Weather Service]weather.govNational Weather ServiceUpper Air10 Dec 2024 — Winds are also derived by using a GPS system that tracks the balloon location to calculate… [National Weather Service]weather.govNational Weather ServiceUpper Air10 Dec 2024 — Winds are also derived by using a GPS system that tracks the balloon location to calculate…
This matters because the sounding is not merely a theoretical model. It is a direct record produced by another balloon moving through the same atmosphere that may have influenced the reported object.
Limits when height and path are uncertain
Upper-air soundings are powerful evidence, but they are not a complete solution. Their usefulness depends on knowing at least something about the object’s location, timing and approximate altitude.
Several limitations commonly arise:
- Unknown height: Witnesses are often poor judges of altitude. A sounding may show several possible wind layers, making it unclear which one affected the object.
- Distance from launch site: The nearest sounding station may be tens or hundreds of kilometres away, and local conditions can differ.
- Timing differences: Most routine soundings are launched at fixed times, often around 0000 and 1200 UTC. Atmospheric conditions may change between the launch and the sighting. [World Meteorological Organization]seedmech.comWORLD METEOROLOGICAL ORGANIZATIONThe purpose of the Guide to Meteorological Instruments and Methods of Observation is to support these ac… [National Weather Service]weather.govNational Weather ServiceUpper Air10 Dec 2024 — Winds are also derived by using a GPS system that tracks the balloon location to calculate…
- Incomplete track information: If witnesses report only a stationary light or a brief glimpse, there may be too little motion data to compare with the wind profile.
For these reasons, a sounding rarely proves the identity of an object by itself. Instead, it serves as a test of consistency. If the reported motion closely matches measured winds at plausible altitudes, the case for a drifting balloon becomes stronger. If the object appears to move in ways that conflict with the sounding across multiple altitude layers, investigators may need to consider other explanations.
What soundings contribute to UFO assessments
Within the broader study of UFO reports caused by balloons and drifting lights, upper-air soundings provide one of the most direct forms of environmental evidence. They replace assumptions about “the wind” with measured wind profiles through the atmosphere. Because balloons routinely pass through layers moving in different directions and at different speeds, apparent turns, accelerations and curved paths are often expected rather than mysterious. Soundings therefore help determine whether unusual-looking motion reflects a genuinely unusual object or simply the changing winds encountered during ascent. [webmet.com]webmet.com9.1.2 Radiosonde Sounding SystemWebMETBy measuring the position of the balloon with respect to time and altitude, wind vectors can be computed that represent the layer-a… [3noaa.gov]noaa.govNational Oceanic and Atmospheric…16 Sept 2025 — The radiosonde is a small instrument package that is suspended below balloon filled wi… [MeteoSwiss]meteoswiss.admin.chMeteo Swiss Weather balloonMeteoSwissWeather balloon - MeteoSwissRadiosondes measure temperature and humidity. Their precise position is recorded using a GPS system…
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Endnotes
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Source: noaa.gov
Link: https://www.noaa.gov/jetstream/upperair/radiosondesSource snippet
National Oceanic and Atmospheric...16 Sept 2025 — The radiosonde is a small instrument package that is suspended below balloon filled wi...
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Source: weather.gov
Link: https://www.weather.gov/epz/upperairSource snippet
National Weather ServiceUpper Air10 Dec 2024 — Winds are also derived by using a GPS system that tracks the balloon location to calculate...
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Source: webmet.com
Title: 9.1.2 Radiosonde Sounding System
Link: https://www.webmet.com/met_monitoring/912.htmlSource snippet
WebMETBy measuring the position of the balloon with respect to time and altitude, wind vectors can be computed that represent the layer-a...
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Source: weather.gov
Link: https://www.weather.gov/upperair/factsheetSource snippet
National Weather ServiceRadiosonde ObservationIf the radiosonde enters a strong jet stream it can travel at speeds exceeding 400 km/hr (2...
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Source: weather.gov
Link: https://www.weather.gov/rah/virtualtourballoonSource snippet
National Weather ServiceCollecting Meteorological Data by Radiosonde or...The radiosonde flight can last in excess of two hours, and dur...
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Source: rosap.ntl.bts.gov
Link: https://rosap.ntl.bts.gov/view/dot/12487/dot_12487_DS1.pdfSource snippet
ROSA PHigh-Altitude Wind Prediction and Measurement...by RL Walterscheid · 2009 · Cited by 10 — It takes an hour or more for balloons to...
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Source: weather.gov
Link: https://www.weather.gov/chs/upperairSource snippet
Weather Balloon / Upper Air ObservationsWeather balloons carry an instrument called a radiosonde which is tracked by specialized ground e...
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Source: aoml.noaa.gov
Title: upper air observations
Link: https://www.aoml.noaa.gov/upper-air-observations/Source snippet
Air Observations: How Weather Balloons Improve...1 Sept 2017 — The radiosondes allow the direct measurement of the upper atmosphere as o...
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Source: weather.gov
Link: https://www.weather.gov/upperair/reqdahdrSource snippet
A Brief History of Upper-air ObservationsUpper air observations began as early as 1749 in Europe with the use of a kite to carry aloft a...
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Source: weather.gov
Link: https://www.weather.gov/gjt/education_corner_balloonSource snippet
Education Corner weather balloonThe weather balloon remains the best platform for observing temperature, wind, relative humidity, and pre...
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Source: ncei.noaa.gov
Link: https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc%3AC00975Source snippet
Global Radiosonde Archive (IGRA), Version 21 Dec 2025 — IGRA Version 2 consists of quality-controlled radiosonde observations of temperat...
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Source: ncei.noaa.gov
Title: weather balloon
Link: https://www.ncei.noaa.gov/products/weather-balloonSource snippet
BalloonThese data are obtained from radiosondes, which are instrument packages tethered to balloons that are launched from the ground, as...
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Source: ncei.noaa.gov
Link: https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc%3AC00145Source snippet
of Winds Aloft - WBAN 120Provisions exist on these forms for listing wind direction and speed at heights up to 42,000 meters. The first p...
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Source: ncei.noaa.gov
Link: https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc%3AC00111Source snippet
Aloft ChartsData contains plotted stations wind direction (36 points) and speed (knots) as wind barbs. The altitude of the plotted winds...
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Source: ncei.noaa.gov
Title: integrated global radiosonde archive
Link: https://www.ncei.noaa.gov/products/weather-balloon/integrated-global-radiosonde-archiveSource snippet
Global Radiosonde Archive (IGRA)The Integrated Global Radiosonde Archive (IGRA) consists of radiosonde and pilot balloon observations fro...
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Source: wpo.noaa.gov
Title: windborne weather balloon reaches new heights
Link: https://wpo.noaa.gov/windborne-weather-balloon-reaches-new-heights/Source snippet
Weather Balloon Reaches New Heights...With an average flight time of 7 days and a maximum flight time of 16, the balloons are capable of...
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Source: imdpune.gov.in
Link: https://imdpune.gov.in/training/upperair/upperairobs.pdf -
Source: meteoswiss.admin.ch
Title: Meteo Swiss Weather balloon
Link: https://www.meteoswiss.admin.ch/weather/weather-and-climate-from-a-to-z/weather-balloon.htmlSource snippet
MeteoSwissWeather balloon - MeteoSwissRadiosondes measure temperature and humidity. Their precise position is recorded using a GPS system...
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Source: community.wmo.int
Link: https://community.wmo.int/observation-components-of-global-observing-systemSource snippet
World Meteorological OrganizationObservation components of the Global Observing SystemFrom a global network of about 1,300 upper-air stat...
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Source: Wikipedia
Title: Weather balloon
Link: https://en.wikipedia.org/wiki/Weather_balloonSource snippet
Weather balloonA weather balloon in preparation for launch Picture taken at approximately 30 km above Oregon using a 1,500 gram weathe...
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Source: Wikipedia
Title: Winds aloft
Link: https://en.wikipedia.org/wiki/Winds_aloftSource snippet
Winds aloftWind direction (DD) and wind speed (ss), displayed as a 4-digit number, e.g. 3127, indicating a wind direction of 310 degre...
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Source: Wikipedia
Link: https://en.wikipedia.org/wiki/RadiosondeSource snippet
RadiosondeA radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measure...
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Source: seedmech.com
Link: https://www.seedmech.com/documents_folder/wmo_no_8.pdfSource snippet
WORLD METEOROLOGICAL ORGANIZATIONThe purpose of the Guide to Meteorological Instruments and Methods of Observation is to support these ac...
Additional References
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Source: ecmwf.int
Link: https://www.ecmwf.int/sites/default/files/elibrary/052025/81661-diagnostics-of-radiosonde-uncertainties.pdfSource snippet
Diagnostics of radiosonde uncertaintiesHowever, the direction differences are fairly constant with height (not shown) which is most consi...
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Source: cdn.knmi.nl
Link: https://cdn.knmi.nl/system/data_center_publications/files/000/066/676/original/teco_windprofile.pdf?1495620579=Source snippet
Air Wind Measurements by Weather RadarWind speed and direction are indicated by wind vanes. Each full barb represents a wind speed of 5 m...
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Source: aos.wisc.edu
Link: https://www.aos.wisc.edu/~hopkins/online/spring/9902wsup.htmSource snippet
online weather supplemental informationThe wind direction at a given level above the surface is determined from the tracking of the motio...
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Source: wmo.int
Link: https://wmo.int/guide-instruments-and-methods-of-observation-wmo-no-8-0Source snippet
Chapter 12. Measurement of upper-air pressure, temperature and humidity. Chapter 13. Measurement of upper wind. Chapter 14.Read more...
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Source: youtube.com
Link: https://www.youtube.com/watch?v=pcLkkoR2LS4Source snippet
Weather Balloons and RadiosondesLearn about how weather balloons are used to study upper-levels of the atmosphere and how the data are co...
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Source: agupubs.onlinelibrary.wiley.com
Title: AGU Publications Global radiosonde balloon drift statistics
Link: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010JD014891Source snippet
AGU PublicationsGlobal radiosonde balloon drift statistics - Seidel - AGU Journalsby DJ Seidel · 2011 · Cited by 106 — Drift distances te...
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Source: community.wmo.int
Title: int Guide to Instruments and Methods of Observation (WMO-No
Link: https://community.wmo.int/site/knowledge-hub/programmes-and-initiatives/instruments-and-methods-of-observation-programme-imop/guide-instruments-and-methods-of-observation-wmo-no-8Source snippet
8)Measurement of upper-air pressure, temperature and humidity. Chapter 13, Measurement of upper wind. Chapter 14, Observation of present...
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Source: journals.ametsoc.org
Title: Errors in the wind and humidity data are also examined. 1
Link: https://journals.ametsoc.org/view/journals/clim/19/14/jcli3804.1.pdfSource snippet
of Balloon Drift Errors in Radiosonde Data on...by R McGrath · 2006 · Cited by 40 — However, the impact of the drift errors on global cl...
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Source: docdb.cept.org
Link: https://docdb.cept.org/download/2081Source snippet
itudes of between 20 and 35 km of the meteorological variables: pressure...Read more...
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Source: hurricanescience.org
Link: https://hurricanescience.org/science/observation/landbased/radiosonde/index.htmlSource snippet
Upper-Air Observations: The RadiosondeThe radiosonde is a small, expendable instrument that is suspended 25 m (about 80 ft) or more below...
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