Most people have no idea what a radiosonde is. And anyone still interested up to this point is asking why anyone would want to track them and then try to find one. But before we get into the tracking and recovery of a radiosonde let us look at what a radiosonde is and does.

A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculate the following variables: altitude, pressure, temperature, relative humidity, wind (both wind speed and wind direction), cosmic ray readings at high altitude and geographical position (latitude/longitude).

Radiosondes may operate at a radio frequency of 403 MHz or 1680 MHz and are an essential source of meteorological data, and hundreds are launched all over the world daily.

A rubber or latex balloon filled with either helium or hydrogen lifts the device up through the atmosphere. The maximum altitude to which the balloon ascends is determined by the diameter and thickness of the balloon. Balloon sizes can range from 100 to 3,000 g (3.5 to 105.8 oz). 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. After bursting, a small parachute on the radiosonde’s support line carries it to Earth. A typical radiosonde flight lasts 60 to 90 minutes. One radiosonde from Clark Air Base, Philippines, reached an altitude of 155,092 ft (47,272 m).

The radiosonde communicates via radio with a computer that stores all the variables in real time. The radiosondes can use a variety of mechanisms for determining wind speed and direction, such as a radio direction finder or GPS. The weight of a radiosonde is typically 250 g (8.8 oz).

Worldwide there are about 1,300 radiosonde launch sites. Most countries share data with the rest of the world through international agreements. Most routine radiosonde launches occur 45 minutes before the official observation time of 00:00 UTC and 12:00 UTC, to provide an instantaneous snapshot of the atmosphere. This is especially important for numerical modeling. In the United States the National Weather Service provides timely upper-air observations for use in weather forecasting, severe weather watches and warnings, and atmospheric research. The National Weather Service launches radiosondes from 92 stations in North America and the Pacific Islands twice daily. It also supports the operation of 10 radiosonde sites in the Caribbean.

So now that you know what a radiosonde is and does let us look at tracking. The interesting people at SondeHub have developed a tracking system. Click on the link below and to understand how to use the tracking system click on the question mark on the top right of the tracking monitor…

SondeHub Tracker

The search and recovery of a radiosonde can be a fun adventure. It also gives one a chance to use their navigation and map reading skills and opportunity to go to an area one might not otherwise think of going.

The radiosondes recovered above are the Vaisala RS41.

And if you are still slightly interested in radiosondes here is a highly informative YouTube video on STM32 Development Boards (Literally) Falling From The Sky.

Radiosonde Recovery Gallery