According to estimates by Deutsche Flugsicherung (DFS), around 15,000 unmanned balloons rise over Germany every year. About half of them are weather balloons from the German Weather Service (DWD), the DWD said at the request of the German Press Agency.

The term weather balloon is actually wrong, said DWD spokesman Andreas Friedrich. Because the balloon filled with helium is only there to transport a radiosonde into the stratosphere. The measuring device, which is attached with a rope and is about the size and weight of a smartphone, transmits readings such as air temperature and humidity to a weather station on the ground.

About 20 weather balloons a day

Twice a day, at 10:45 a.m. and 10:45 p.m., the balloons rose at a speed of about 18 kilometers per hour. The expandable balloons are three to five meters high on the ground and up to 40 meters at the highest point. After about an hour and a half, at an altitude of around 30 kilometers, the thin latex balloon burst. A parachute unfolds and the probe flies to the ground in about an hour and a half. The scraps of latex also end up on the ground. According to the DWD, one of around 20 daily flights costs around 250 euros.

The probe is then no longer needed and remains where it lands. Depending on the strength of the wind speed when ascending or descending, it can cover a distance of up to 300 kilometers from the starting point to the landing point. Aviation fans and geocachers often collected the probes to take home, Friedrich said.

Children's birthday balloons

According to its own statements, the DFS knows little about the weather and research balloons. They fly significantly higher than airplanes and therefore do not need clearance. A large part of the balloons in German airspace are certain children's balloons, for example from birthday parties.

But are all balloons really harmless? According to the Bundeswehr's geoinformation service, it uses balloons to collect weather data or to calculate the trajectory of ballistic projectiles. There are no balloons for military purposes, a spokesman said. To the knowledge of the Bundeswehr, there are no foreign military balloons, such as spy balloons, over Germany.

The Bundeswehr can shoot down a balloon if it poses a military threat after legal approval, the spokesman said. NATO decides whether a balloon poses a military threat.