So....I recently commented your video about the two Vaisala radiosondes, sadly some of the people in the comment section think that radiosondes are a waste of time, money and overall are just pointless pollution.
Because I know something about radiosondes (enough qualification?) I want to correct and explain some misconceptions about those.
1. Why arent they recovered?
To answer this I have to go back in time a few years.
back in the old days radiosondes were heavy, complex and expensive..weather organisations often tried to recover them or there was a sticker on them which said something like: If you send it back, we will give you money. Those returned sondes were send back to the company, repaired,recalibrated and then shipped out again, today this just would not be economically, electronic is cheap to manufacture and small, the only real magic part of a todays radiosonde is the sensor arm, all the other things are pretty standard.
Some people also suggested to send a person in a van all around the country to collect the sondes, this also isnt possible the way some folks find:
1. You cant collect radisondes which stopped transmitting, I tried it a few times without luck, maybe you have a change when it lands on a big flat field and you can spot it with binoculars or so but surely not in a region like Austria or germany.
2. Monitoring stations are loosing the signal in a height of 200-2500m, this depends on the distance and region but it can be said for sure that it is not possible to calculate what a radiosonde does in the last 2000m of coming down to the ground, if there are funny winds they can fly kilometers(!) away from the predicted landing point, so it is not possible to predict the point of touchdown as accurately as it would be needed to collect a sonde a few days after.
If you want to catch a sonde you would normaly drive in the predicted region and try to receive the signal there to get readings to reasonable heights, but even then you can be unlucky, maybe it sails hundreds of meters or so just in the last 100m. Then you need a handheld radio and a directional antenna to search for the sonde, this may take hours if you are unlucky with the terrain or if you have reflections due to rocks or trees. But even if you can localise a sonde visually it may be high up on a tree or somewhere else where it is unreachable.
3. There are sondes which just land in absolutely unrechable terrain, nobody will risk his life to collect a sonde which landed on a glacier in the middle of an avalanche path, even in the summer, its dangerous to go offside paths, despite that, you are working against the battery life all the time.
This may be different in some really flat regions.
4. They are just not worth it, a radiosonde costs about 200-300 Euros, then you need a balloon and the gas to fill it furthermore a small parachute (some stations skip this) overall one launch will cost you about 350-500 Euros with a normal sonde like rs41 or rs92.
The parachute,balloon and gas cant be reused obviously, the sonde itself is maybe broken, even if not it would be necessary to recalibrate and clean it, then you also have to pay shippin from and to the manufacturer...thats just crazy, it is the cheapest way to just buy new ones with guaranteed measurement accuracy.
But there are exceptions, for example you get 30 Euros if you resend a ozone sonde to the german weather bureau (DWD), this ozone sensor can be attached to the radiosonde (in reality the radiosndes are attached to the senor because it alot bigger), then they are send up as one sonde, they have seperated batteries but the sensor is linked to the radiosonde via cable to send the collected data over the radiosonde as some sort of wireless modem:)
Indeed there are some other external sensor like aerosol,radioactivity,UV-Light,dewing point etc. these are expensive and they want it back if you find a sonde with such a sensor attached.
This sondes are currently used in northern/west europe:
RS41 from Vaisala (current standard sonde in europe [by launched value] since 2017-2018)
RS92 from Vaisala (standard sonde from 2004-2017)
DFM09 from Graw (often used by germany military and universities)
DFM06 from Graw (older model, often used by german military and universities)
PS15 from Graw (cheaper so called "Pilotsonde" hasnt got sensor, only GPS for wind measurements)
MRS-SRS-C34 from Meteolabor (rare sonde, sometimes used in switzerland)
SRS-C50 from Meteolabor (also quite rare, can be seen in germany sometimes)
M2K2 from Meteomodem (often used in France)
What do I need to find some myself?
Time and nerves
SDR or receiver with packet audio output (unfiltered audio for digital decoding)
Sondemonitor or some other decoder
Handheld scanner with 403 Mhz Yagi antenna
Attenuators for near field search
Online tracking sites like Wetterson.de
For your home a helical antenna can be recommended, these are ideal for receiving radiosondes.
Thank you for reading