The Radiosonde reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Radiosonde

A radiosonde is a unit for use in weather balloons that measures various atmospheric parameters and transmits them to a fixed receiver. A frequency band at 403 MHz is reserved for radiosondes.

The device is tied to an helium filled baloon, which lifts the device up through the atmosphere. The balloon bursts at about 30000 meters due to lack of external air pressure at that altitude. The modern rawinsonde communicates via radio with a computer that stores all the variables at real time. The first rawinsondes were observed from the ground with a theodolite, and gave only a wind estimation by the position.
The most important variables measured by a modern radiosonde are:

• Pressure
• Altitude
• Geographical position (Latitude/Longitude)
• Temperature
• Relative humidity
• Wind speed and direction
• Some also give ozone concentration.

With the data, is possible to draw Stüve diagrams, which are useful for the interpretation of phenomena such as thermical inversion.

The weight of a radiosonde is typically 250 gramss. A major manufacturer is Vaisala in Finland.

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