Weather balloons are latex balloons that carry an instrument package (a radiosonde) straight up through the atmosphere, measuring the vertical profile of temperature, humidity, pressure, and winds and transmitting it back by radio in real time. Those profiles are a primary data source for numerical weather prediction, severe‑weather diagnosis, aviation and fire‑weather forecasting, and climate/air‑quality research.[1][2][3][4][5]
Basic setup and launch
- A large latex balloon is filled with hydrogen or helium and tethered to a small instrument box called a radiosonde, often with a parachute beneath the balloon for a safe descent when it bursts.[6][3][4]
- Before launch, the radiosonde is powered on, synchronized with a ground receiver, and its sensors are checked; then the balloon is released from a weather station (e.g., NWS upper‑air sites).[7][8][4]
- Standard operational balloons are launched about every 12 hours at hundreds of sites worldwide, giving twice‑daily snapshots of the 3D atmosphere.[2][4][7]
How they rise through the atmosphere
- The gas in the balloon is much less dense than the surrounding air, so buoyancy lifts the system upward at roughly 4 m/s or about 300 m/min (around 1,000 ft/min).[2][8][4]
- As the balloon ascends into lower pressure, it expands dramatically—eventually reaching several meters across before the latex can’t stretch further and the balloon bursts, typically around 20–30 km altitude (near or into the lower stratosphere).[9][6][5]
- After burst, the radiosonde falls under a small parachute, which slows descent so it is less hazardous and can sometimes be recovered for reuse or research.[6][8][3]
What instruments measure
A radiosonde is essentially a compact vertical weather station plus GPS and a radio transmitter. Common measurements:[7][3][5]
- Temperature: A small thermistor or similar sensor exposed to the airflow measures air temperature continuously during ascent.[3][5][7]
- Humidity: A capacitive or resistive humidity sensor measures relative humidity; together with temperature this yields dew point.[1][7][3]
- Pressure: A pressure sensor inside the radiosonde measures air pressure, which also serves as a proxy for altitude when combined with the hydrostatic equation.[5][7][3]
- Wind (speed and direction): GPS records the radiosonde’s changing position; by differentiating position with time, the ground system computes horizontal wind speed and direction at each level.[4][7][5]
- Position/altitude: GPS also provides an independent measurement of altitude and horizontal location, which helps quality‑control the vertical profile and wind derivation.[4][5]
Some specialized payloads (research balloons, student projects, or advanced long‑duration systems) may add ozone sensors, radiometers, cameras, or particle counters, but the operational core is T–RH–P–wind.[10][9][11]
How data are transmitted during ascent
- The radiosonde samples its sensors roughly once per second, so at 4 m/s ascent you get data about every 2–4 meters vertically—an extremely fine resolution sounding.[2][3][5]
- A small battery‑powered radio transmitter sends these measurements in real time down to a dedicated ground receiver at the launch site.[8][3][4]
- The ground system decodes the radio signal into a vertical profile of pressure, temperature, humidity, and winds that is then formatted and sent into national and global meteorological networks.[12][7][4]
The vertical profile (“sounding”)
The end product is a thermodynamic and kinematic profile of the atmosphere from the surface to the mid‑stratosphere.[1][2][7]
- Meteorologists plot the data on diagrams like a Skew‑T log‑P: temperature and dew point versus pressure, with wind barbs along the side.[7][1]
- From this single balloon ascent you derive stability indices, mixing depth, lifting condensation level, CAPE/CIN, shear, freezing levels, and cloud layers—essentially a cross‑section of the column above the station.[12][1][7]
Why balloon data are so useful
Even with satellites and radar, these in‑situ vertical soundings are still foundational. Some key uses:[1][4][5]
- Numerical weather prediction: Upper‑air soundings are one of the primary initial‑condition data sources for global and regional forecast models; they constrain temperature, moisture, and winds at many levels.[12][4][1]
- Severe weather forecasting: Soundings reveal instability, capping inversions, and vertical wind shear, which are crucial for assessing thunderstorm and tornado potential, storm mode, and storm motion.[7][1][12]
- Aviation and marine: Pilots and marine forecasters use wind and temperature profiles to anticipate turbulence, icing, jet‑stream location, and cloud tops/ceilings.[4][7]
- Fire weather: Vertical moisture and stability profiles inform plume behavior, mixing heights, and transport winds, all important for wildfire behavior and smoke dispersion.[4]
- Air quality and dispersion: Profiles of stability, mixing height, and winds feed into pollution dispersion models and smoke/chemical transport forecasts.[1][4]
- Climate and research: Long‑term radiosonde records form one of the few consistent multi‑decadal datasets of upper‑air temperature and humidity, useful for detecting trends and validating reanalyses and satellite retrievals.[5][1][4]
Newer and extended balloon systems
- Traditional radiosondes provide a single ascent profile over 1–2 hours, then are done once the balloon bursts.[1][4]
- Newer long‑duration and controllable balloons (e.g., WindBorne systems) can adjust altitude to make multiple vertical profiles during a multi‑day flight, especially over poorly observed regions like oceans or storm genesis zones.[10]
- These platforms can greatly increase the density of upper‑air observations in regions where fixed launch sites are sparse, improving forecasts of high‑impact systems.[10]
Given your interest in hydrology and local weather on the Prairies, would you like a practical example of reading a Skew‑T from a nearby Alberta sounding and tying it to convective potential or precipitation type?
⁂
- https://www.wvtf.org/2024-05-13/the-all-important-weather-balloon
- https://scied.ucar.edu/learning-zone/atmosphere/weather-balloons
- https://www.weather.gov/media/key/KEY - Weather Balloon Poster.pdf
- https://www.weather.gov/rah/virtualtourballoon
- https://www.meteoswiss.admin.ch/weather/weather-and-climate-from-a-to-z/weather-balloon.html
- https://www.youtube.com/watch?v=AnQraD7jSG4
- https://www.weather.gov/ilx/ua-tour
- https://www.youtube.com/watch?v=yf0d1tG4UvI
- https://en.wikipedia.org/wiki/Weather_balloon
- https://wpo.noaa.gov/windborne-weather-balloon-reaches-new-heights/
- https://www.sciencedirect.com/science/article/pii/S2468067218300579
- https://www.youtube.com/watch?v=mFCsqwYRzKU
- https://www.weather.gov/gjt/education_corner_balloon
- https://www.youtube.com/watch?v=J6rCy2OnzVE
- https://www.weathershack.com/blogs/news/how-balloon-weather-sensors-collect-atmospheric-data
Yes show me a Skew T for Alberta
You can view live and forecast Skew‑T diagrams for Alberta using a few web tools; the clearest option is an interactive map where you click near your location and it generates a sounding from model data. Below is how to get a Skew‑T for central Alberta right now and how to read the basics off it.[1][2]
Getting a Skew‑T near you
Two practical options you can use in a browser:
- Skewtpy interactive map: Go to the SkewT CAPE Weather Forecasting site, zoom to Alberta, then either click a radiosonde station (Edmonton/Stony Plain) for an observed Skew‑T, or click anywhere nearby to generate a model‑derived Skew‑T for that point and time.[1]
- Windy.com soundings: On Windy, zoom to central Alberta, right‑click (or long‑press) near your point of interest and choose “Show sounding / Skew‑T” to see a forecast Skew‑T and basic indices for that location and forecast hour.[2]
If you’d like, I can walk you through a specific example for “near Calgary” or “near Red Deer” step‑by‑step using one of these tools.
What you see on a Skew‑T
A standard Skew‑T log‑P diagram has a fixed layout, regardless of location.[3][4]
- Vertical axis: Pressure in millibars (hPa) decreasing upward (from about 1000 hPa near the surface to 100 hPa and above), so height increases as you go up the page.[4][3]
- Temperature lines: Diagonal lines slanting up to the right (this “skew” of the isotherms is where the diagram gets its name).[3][4]
- Plotted profiles:
- Temperature (T) is a red line following the measured/model air temperature with height.[5][3]
- Dewpoint (Td) is a green or blue line, showing moisture; where T and Td are close, the air is near saturation and clouds are likely.[5][3]
- Wind barbs: Plotted along the right side at various pressure levels, showing wind direction and speed at those levels.[3][5]
Reading CAPE, CIN, and stability (high level)
Once you have a Skew‑T for an Alberta location, you can extract convective information:[4][5][3]
- Parcel path: Lifting a surface or mixed‑layer parcel gives a dashed “parcel temperature” curve; where this parcel is warmer than the environment you have positive buoyancy.[5][3]
- CAPE: The area between parcel temperature and environmental temperature where the parcel is warmer (usually shaded in red on many tools). More area means more potential updraft strength and convective intensity.[1][3][5]
- CIN: The area where the parcel is cooler than the environment below its level of free convection (LFC); this cap must usually be eroded by heating or forcing before storms can initiate.[3][5]
Many online tools (including Skewtpy and Windy) compute and print CAPE, CIN, LCL, LFC, equilibrium level, and lifted indices directly next to the diagram, so you can link the numbers to the shaded areas visually.[2][1][3]
Alberta‑specific use
For central Alberta in convective season, a Skew‑T lets you quickly see:
- Depth of the mixed layer and how dry the boundary layer is, which affects evaporative cooling and gust‑front strength.[5][3]
- Height and strength of any capping inversion that often suppresses convection until late afternoon.[3][5]
- Shear profile in the lowest 6 km for assessing storm mode (pulse vs. multicell vs. supercell).[1][3]
If you tell me a specific point (e.g., “near Red Deer” vs. “just east of Calgary”) and whether you care more about “right now” or a particular forecast time, I can walk you through how to interpret that Skew‑T step‑by‑step for storm or precipitation potential.
⁂
- https://www.skewtpy.com
- https://www.windy.com/38.355/-93.679
- https://www.weather.gov/source/zhu/ZHU_Training_Page/convective_parameters/skewt/skewtinfo.html
- https://www.weather.gov/media/ohx/PDF/TheskewTlogPdiagram.pdf
- https://flsc.org/portals/12/PDF/Read_Skew_T.pdf
- https://www.encweather.com/skewt/
- https://www.weather.gov/upperair/SkewTViewing
- https://www.eoas.ubc.ca/books/Practical_Meteorology/common/3-SkewT-v9.1color.pdf
- https://www.eas.ualberta.ca/jdwilson/EAS372_13/urls.html
- https://www.youtube.com/watch?v=9yLb9qF__yc
I want a winter Skew T example for snow
For an all‑snow winter profile, you want a Skew‑T where the temperature stays below freezing through the whole cloud/precipitation layer and the column is quite moist. You can then contrast that with profiles that have a “warm nose” aloft, which produce sleet or freezing rain instead.[1][2][3]
Textbook “all snow” Skew‑T
The U.S. NWS JetStream site has a nice canonical snow Skew‑T example that generalizes well to Alberta winters. Key signatures:[1]
- Temperature profile:
- The red temperature line stays left of (colder than) the 0 °C isotherm from near the surface up through most of the troposphere (e.g., from roughly 900–700 hPa and higher).[3][1]
- There may be a shallow inversion a few hundred meters above the ground, but temperatures within that inversion are still below 0 °C, so nothing melts.[1]
- Moisture profile:
- The dewpoint line (often blue) lies very close to the temperature line through the layer where precipitation is forming, indicating a nearly saturated column (relative humidity near 100%).[4][1]
- At the surface, the air is also sub‑freezing and fairly moist, so the snowflakes survive to the ground without much melting or sublimation.[2][1]
Physically, precipitation forms as ice in the cold cloud, falls through entirely sub‑freezing air, and reaches the surface as snow.[2][3][1]
Snow vs. sleet vs. freezing rain on Skew‑T
A winter Skew‑T becomes really interesting when you look at how small changes in the vertical temperature profile change precipitation type.[3][2][1]
- Pure snow:
- Temperatures from about 1,000 m above ground up to the top of the cloud layer remain below 0 °C.[2][3]
- Surface is at or below 0 °C and the layer is moist (T and Td nearly together).[4][1]
- Sleet (ice pellets):
- Snow forms aloft in a cold layer, then falls into a mid‑level “warm nose” where T rises above 0 °C and partially or fully melts the flakes.[3][1][2]
- Below that, there is a fairly deep sub‑freezing layer near the surface, cold enough and thick enough for the melted drops to refreeze into ice pellets before hitting the ground.[1][3]
- Freezing rain:
- Again, snow forms in cold air aloft but then passes through a deeper or warmer above‑freezing “warm nose,” fully melting into rain.[2][3][1]
- The surface layer is sub‑freezing but very shallow, so the drops don’t have time to refreeze in the air; they freeze on contact with exposed surfaces.[3][1][2]
These are all visible on the NWS snow/ice Skew‑T examples and in tutorials that step through real winter cases.[5][1][2][3]
Practical checklist for “snow sounding”
When you pull up a winter Skew‑T for central Alberta (e.g., Edmonton/Stony Plain or Calgary) and want to quickly answer “snow or no snow?” you can run this mental checklist:[1][2][3]
- Is there a saturated layer (T and Td close) where vertical motion and cloud are expected?
- From the top of that saturated layer down to at least 1 km above ground, does the temperature stay below 0 °C (no warm nose)?
- Is the near‑surface layer also at or below 0 °C, and at least a few hundred meters deep?
If the answer is “yes” to all three, you’re looking at a classic all‑snow profile; you can then use other fields (omega, dendritic growth zone, snow‑liquid ratio guidance) to refine intensity and density estimates.[6][7][2]
Would you like to walk through a specific kind of winter case next—heavy all‑snow, or a marginal setup where a small warm nose decides between snow and freezing rain?
⁂
- https://w2.weather.gov/jetstream/skewt_samples
- https://study.com/academy/lesson/forecasting-winter-weather-with-a-skew-t-diagram.html
- http://www.theweatherprediction.com/habyhints/167/
- https://www.wvtf.org/2025-01-20/breaking-down-winter-precipitation-types
- https://www.youtube.com/watch?v=QJKldQ7AHws
- https://www.youtube.com/watch?v=5GXA6WcfAt4
- https://www.meted.ucar.edu/resources/mesoprim/skewtd3/index.html?ls=hail_q.json
- https://www.youtube.com/watch?v=RidaWM2E8eQ
- https://www.weather.gov/zse/ModelSounding?id=kjfk&model=rap
- https://thecloudonline.net/blog/basic-skew-t-analysis-snow-or-no-snow/
- https://www.youtube.com/watch?v=iMg8xEHnh-E
- https://www.angelfire.com/pa2/weatherdevil/winterstuff.htm
- https://www.youtube.com/watch?v=JsBI4z0pSVs
- https://www.weather.gov/source/zhu/ZHU_Training_Page/convective_parameters/skewt/skewtinfo.html
- https://www.spot-on-weather.com/uploads/9/4/6/3/94633598/forecasting_weather_using_skew.pdf
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