What is a radiosonde?
Radiosondes are meteorological instruments used to get some important atmospheric data at various heights. These instruments are equipped with very precise sensors that are capable of getting parameters such as temperatures, humidity, atmospheric pressure and also wind speed.
The picture shows a radiosonde from Switzerland, that landed in Italy after a long flight. This radiosonde was recovered by Pio IN3WZS.
The information gained, together with the sonde position (there is an onboard GPS), are transmitted via radio signal back to ground, where some ground stations receive that data and process them in order to provide us with weather forecast.
Radiosondes are attached to a flying balloon by a long nylon string. The balloon has a diameter of around 3 meters at ground level, but it can easily reach up to three times this value when it’s high up in the sky (~30 km).
At some point, the balloon will eventually explode because of the extremely low air pressure: the parachute inside of the balloon it’s relased and opens, starting the descending phase.
There are a variety of radiosondes, and there are also external modules like pressure sensors or ozone sounding systems that can be attached to the standard sonde.
Radiosondes are really important because they enable us to understand the structure of the atmosphere and do weather forecast, but they also permit us to monitor parameters that are really important for aviation and leisure activities such as paraglider.
They also help researchers to monitor the effects of the global warming.
Recover a radiosonde
When the balloon explodes and the parachute opens, the sonde starts it’s descending phase, during which it continues transmitting it’s position.
By using special receivers or websites such as SondeHub or Radiosondy, we can receive and decode the data, in order to get the exact position of the sonde in real-time.
Once the sonde fall to the ground, we can recover it. Many radio ham and non-ham people, find this geocatching radio adventure very entertaining.
Radiosondes are tipically launched twice a day at 00 and 12 UTC.
You can see which data are being received by my two ground stations at tracker.natmus.net
When you finally find the sonde, you can keep it!
But please, if you do find a sonde, report the recovery on one of the sites mentioned above!
There are also clubs that share information to help their members find the sonde, and share their adventures.