Radiosonde
The first flights of aerological instruments were done in the second half of the 19th century with kites and meteographs, a recording device measuring pressure and temperature that would be recovered after the experiment.
In 1924, Colonel William Blaire in the U.S. Signal Corps did the first primitive experiments with weather measurements from balloon, making use of the temperature dependence of radio circuits.
The first true radiosonde that sent precise encoded telemetry from weather sensors was invented in France by Robert Bureau [fr].
Molchanov's design became a popular standard because of its simplicity and because it converted sensor readings to Morse code, making it easy to use without special equipment or training.
[6] Working with a modified Molchanov sonde, Sergey Vernov was the first to use radiosondes to perform cosmic ray readings at high altitude.
On April 1, 1935, he took measurements up to 13.6 km (8.5 mi) using a pair of Geiger counters in an anti-coincidence circuit to avoid counting secondary ray showers.
[8] The NBS gave the project to Harry Diamond, who had previously worked on radio navigation and invented a blind landing system for airplanes.
In 1937, Diamond, along with his associates Francis Dunmore and Wilbur Hinmann, Jr., created a radiosonde that employed audio-frequency subcarrier modulation with the help of a resistance-capacity relaxation oscillator.
[12] Due to this and other improvements in cost (about $25), weight (> 1 kilogram), and accuracy, hundreds of thousands of NBS-style radiosondes were produced nationwide for research purposes, and the apparatus was officially adopted by the U.S.
Although modern remote sensing by satellites, aircraft and ground sensors is an increasing source of atmospheric data, none of these systems can match the vertical resolution (30 m (98 ft) or less) and altitude coverage (30 km (19 mi)) of radiosonde observations, so they remain essential to modern meteorology.
[16] After bursting, a small parachute on the radiosonde's support line may slow its descent to Earth, while some rely on the aerodynamic drag of the shredded remains of the balloon, and the very light weight of the package itself.
Radiosondes weather balloons have conventionally been used as means of measuring atmospheric profiles of humidity, temperature, pressure, wind speed and direction.
Reliable and timely information underpin society’s preparedness to extreme weather conditions and to changing climate patterns.
Because a sonde may drift several hundred kilometers during the 90- to 120-minute flight, there may be concern that this could introduce problems into the model initialization.
[26] This issue may in future be solved by weather drones, which have precise control over their location and can compensate for drift.
[27] Lamentably, in less developed parts of the globe such as Africa, which has high vulnerability to impacts of extreme weather events and climate change, there is paucity of surface- and upper-air observations.
The vast data gap in such a large part the global landmass, home to some of the most vulnerable societies, the aforementioned call has galvanised a global effort[29] to “plug the data gap” in the decade ahead and halt a further deterioration in the observation networks.
