Editing Radiosonde (section)

== Operation ==
A [[rubber]] or [[latex]] balloon filled with either [[helium]] or [[hydrogen]] lifts the device up through the [[Atmosphere of Earth|atmosphere]]. The maximum altitude to which the balloon ascends is determined by the diameter and thickness of the balloon. Balloon sizes can range from {{convert|100|to|3000|g|abbr=on}}. As the balloon ascends through the atmosphere, the pressure decreases, causing the balloon to expand. Eventually, the balloon will expand to the extent that its skin will break, terminating the ascent. An {{convert|800|g|abbr=on}} balloon will burst at about {{convert|21|km|abbr=on}}.<ref>Dian J. Gaffen. [http://www.aero.jussieu.fr/~sparc/News12/Radiosondes.html Radiosonde Observations and Their Use in SPARC-Related Investigations.] {{webarchive |url=https://web.archive.org/web/20070607142822/http://www.aero.jussieu.fr/~sparc/News12/Radiosondes.html |date=June 7, 2007 }} Retrieved on 2008-05-25.</ref>  After bursting, a small [[parachute]] on the radiosonde's support line may slow its descent to Earth, while some rely on the aerodynamic drag of the shredded remains of the balloon, and the very light weight of the package itself.  A typical radiosonde flight lasts 60 to 90 minutes.  One radiosonde from [[Clark Air Base]], Philippines, reached an altitude of {{convert|155092|ft|abbr=on}}.

The modern radiosonde communicates via radio with a computer that stores all the variables in real time. The first radiosondes were observed from the ground with a [[theodolite]], and gave only a wind estimation by the position. With the advent of radar by the Signal Corps it was possible to track a radar target carried by the balloons with the [[SCR-658 radar]]. Modern radiosondes can use a variety of mechanisms for determining wind speed and direction, such as a [[radio direction finder]] or [[Global Positioning System|GPS]]. The weight of a radiosonde is typically {{convert|250|g|abbr=on}}.

Sometimes radiosondes are deployed by being dropped from an aircraft instead of being carried aloft by a balloon. Radiosondes deployed in this way are called [[dropsonde]]s.