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Our first radiosonde 
Windsond S1

 Windsond is the first weather balloon system thta Sparv made for an immediate view of local conditions. 

While the model is not produced anymore, you can find all the information on this page.

Our first radiosonde
Windsond S1

 Windsond is the first weather balloon system thta Sparv made for an immediate view of local conditions. 

While the model is not produced anymore, you can find all the information on this page.

Extremely compact design

Uniquely small size for easy transport and deployment, enabling lightweight canisters and lower logistics overhead

Helium-efficient and reusable

Saves precious helium and reduces canister size; sondes are recoverable and reusable for best economy

Real-time atmospheric profiling

Live wind, temperature, and humidity profiles with user‑friendly ground‑station software and reliable recovery (even days later)

Predictable recovery and control

Tools to predict and control landing location, simplifying retrieval and outreach deployments

More than 10 000+ units sold

More than 

10 000+ 

units sold

Hardware

1

Sonde

  • Measure wind direction, wind speed and temperature
  • Hygrometer to measure air humidity and dew point (additional option)
  • Barometer to improve the altitude accuracy from 100m to 7m
  • Simple sonde activation by a switch. Sounds indicate when the sond is ready for launch.
  • Reusable sondes as an option with added cut-down wires and smart tracking features.
  • Sonde cut-down altitude (reusable sondes) configurable by user, also during flight
  • Maximum altitude 8-9 km meter above sea level (26-30 thousand feet)
  • Radio link with programmable frequency and transmission power.
  • Specially developed error correcting code for more robust radio link.
  • No heavy metal content for small environmental impact.

2

Ground Station

  • Review weather conditions even as the balloon ascends
  • Weather conditions are reported in graphical and text formats and exported to file in “Winds” format
  • Automatic averaging and interpolation of measurements
  • Follow the balloon live on Google Earth, right from launch to landing
  • Multiple sonds and multiple receivers are supported
  • Change settings with convenient graphical user interface
  • Keep another sond in the car to compare the positions of the balloon and the car
  • Load earlier soundings to revisit the measurements or replay the flight


Find full specifications and options in the Windsond product catalogue (1.1 MB).

Software

1

Sonde Control

    • Bi-directional radio communication with the sonde before, during and after soundings
    • Check sonde status at a glance with the sub-system status panel   
    • Check sonde status and behaviour
    • Choose sonde cut-down altitude trigger
    • Predict, visualize and control sonde landing location to make sonde recovery easy
    • Follow the balloon live on Google Earth or OziExplorer, right from launch to landing
    • Support for 8 simultaneous sondes (customizable with Swarmsonde and/or Multisonde)
    • Support for multiple receivers

2

Customization

Sparv Embedded looks forward to serving your specific needs with custom software development.

Sonde reuse

“Recovery rates of 90% can be expected”

The Windsond radiosondes are designed for reuse. While the small size makes for minimal environmental impact if not recovered and the sondes are affordable even as is, the easy and dependable recovery can make the price of each sounding marginal.  

Operation sequence:  

  1. Turn on the sonde by sliding the switch. Wait for the sonde to acquire a GPS fix. Release the sonde.  
  2. The sonde measures and transmits data to the ground  
  3. At the set peak altitude, the sonde detaches from the balloon tether line. The sonde starts to fall.  
  4. When the sonde has landed, it will blink and beep to be easier to find.  

Three factors helps the recovery:


1

Pick a convenient landing site 

Specially developed algorithms lets the user choose landing site with about 50m accuracy. The sonde has the capability to do a controlled cut-down from the balloon based on altitude or at direct trigger from the ground station, transmitted via radio. A map shows predicted landing locations depending on the altitude where the sonde should let go from the balloon to fall back to earth. These locations form a line throughout the landscape where a landing is possible given the current wind conditions. The user can change the peak altitude at any time to make the sonde land in an easily accessible location.

2

Get landing coordinates

The ground station updates the predicted landing location as the sonde falls, even if radio contact is lost. The final location is known with about 10 meters of uncertainty. The upcoming Android ground station shows the way to the sonde on a map and as a compass arrow.

3

Sonde beeps and blinks

The operator makes way to the landing site, where the sonde restores radio contact and starts to blink and beep. Even if landing in snow or rough terrain, finding the sonde is easy.  

The power-save mode makes the sonde lay dormant for days before activated by the proximity of the ground station.  

This short clip shows how easy the sonde is to spot even in fresh snow.

Articles

Several researchers have been using Windsond, here is a non exhaustive list of articles in which Windsond is used for scientific purpose: 

  • Markowski, P.M.; Richardson, Y.P.; Richardson, S.J.; Peterson, A., Aboveground thermodynamic observations in convective storms from balloon borne probes acting as pseudo-lagrangian drifters., Bull. Am. Meteorol. Soc.2018, 99, 711–724.
  • Bessardon, G.E.Q.; Fosu-Amankwah, K.; Petersson, A.; Brooks, B.J., Evaluation of Windsond S1H2 Performance in Kumasi during the 2016 DACCIWA Field Campaign., Atmos. Meas. Tech. 2019, 12, 1311–1324.
  • White, L.D.; Lu, D., Multi-Scale Transects of Three North American Drylines., Atmosphere 2020, 11, 854.
  • Castellnou, M.; Bachfischer, M.; Miralles, M.; Ruiz, B.; Stoof, C.R.; Vila-Guerau de Arellano, J., Pyroconvection Classification Based on Atmospheric Vertical Profiling Correlation With Extreme Fire Spread Observations, JGR Atmospheres. 2022, Volume127, Issue22
  • C. Lyn Comer, Braedon Stouffer, David J. Stensrud, Yunji Zhang, Matthew R. Kumjian, An Automated Approach to Estimating Convective Boundary Layer Depth from Dual-Polarization WSR-88D Radar Observations, Journal of Atmospheric and Oceanic Technology, 41(8), 767-780. https://doi.org/10.1175/JTECH-D-23-0166.1
  • Soderholm, J. S., M. R. Kumjian, J. P. Brook, A. Peterson, A. Protat, J. Brimelow, S. Trömel, and M. Kunz,, 2025: Measuring Hail-like Trajectories and Growth with the Hailsonde., Bull. Amer. Meteor. Soc., 106, E2128–E2142, https://doi.org/10.1175/BAMS-D-24-0021.1.
  • Crosman, E., A. M. Ward, S. W. Bieda, T. T. Lindley, M. Gittinger, S. Pal, and H. Vepuri,, 2023: Engaging Undergraduate Students in Collaborative Field Research with the U.S. National Weather Service: The SCORCHER Study., Bull. Amer. Meteor. Soc., 104, E652–E659, https://doi.org/10.1175/BAMS-D-22-0113.1.
  • Fischer, J., Groenemeijer, P., Holzer, A., Feldmann, M., Schröer, K., Battaglioli, F., Schielicke, L., Púčik, T., Antonescu, B., Gatzen, C., and TIM Partners:, Invited perspectives: Thunderstorm intensification from mountains to plains, Nat. Hazards Earth Syst. Sci., 25, 2629–2656, https://doi.org/10.5194/nhess-25-2629-2025, 2025.

Media

David Templeton, Pittsburgh Post-Gazette. Nov 24, 2017, “Stupidly simple” way to use party balloons to study tornadoes., Download as PDF 

Matthew Cappucci, The Washington Post. July 25, 2019, This team of scientists launches weather balloons into violent storms. What they learn could improve tornado forecasts.,  Link

Stephanie Kossman, Brookhaven National Laboratory Newsroom, July 19, 2022, Mapping Urban Heat From the Ground Up, Link

Video:  Pyroconvection Classification Based on Atmospheric Vertical Profiling, January 27, 2023