The UFO often seen in the sky could be this!

Recently, an unmanned airship used for meteorological and other scientific research has become a hot topic. This "wandering" balloon is a stethoscope at an altitude of 10,000 meters - a weather sounding balloon. It is often mistaken for a UFO, but meteorological workers affectionately named it "Dabai", and "brave and fearless high-altitude explorer" is also the highest evaluation for it.

A weather balloon is a device used to detect meteorological elements such as temperature, humidity, air pressure, wind direction, and wind speed from near the ground to 35 km in the air. So how does it accomplish the high-altitude detection mission?

Composition of meteorological sounding system and functions of each department

0 1

Weather balloon

The sounding balloon is the carrier of the entire detection equipment. Like a carrier rocket, it carries the sounding instrument to high altitude at a speed of 6-8m/s to realize the detection of high-altitude meteorological elements.

There are several specifications of sounding balloons, which are generally distinguished by weight, including 300 grams, 750 grams, 1600 grams, etc. Different specifications are selected according to different requirements for detection altitude. The heavier the balloon, the higher the detection altitude. The balloon is generally filled with hydrogen or helium. After inflating, a 1600-gram balloon can reach a diameter of 2.5 meters on the ground. As the air pressure decreases at high altitude, the balloon will slowly expand, and finally explode to a diameter of 8-11 meters, which is spectacular.

In addition, in addition to serving as a carrier, the wind direction and wind speed are also calculated based on the horizontal displacement of the sounding balloon.

0 2

Sonde

The sonde is the core component of high-altitude detection. It is composed of temperature, humidity, and air pressure sensors, as well as measurement circuits, control (decoding) circuits, transmitting circuits and batteries. After the sonde is carried to high altitudes by a sounding balloon, it continuously collects meteorological data such as temperature, humidity, and air pressure, and communicates with the data receiving radar on the ground to transmit the collected data back to the ground meteorological station.

03

Ground receiving radar

The ground receiving radar starts tracking the moment the sounding balloon carrying the sonde is released. The radar antenna tracks wherever the balloon and the sonde fly until the sounding balloon explodes. It also keeps communicating with the sonde in the form of asking and shaking hands to receive the data collected by the sonde.

The process of sounding balloon detection

When working, the ground radar uses real-time tracking of the sounding balloon to realize the wind measurement function. The sounding balloon carries the sonde into the air. As the balloon rises, the ground radar sends out an inquiry signal, and the sonde transponder sends out a reply signal in response. According to the time interval between each pair of inquiry and reply signals and the direction of the signals, the position of the sounding balloon at each moment can be determined, that is, its straight-line distance from the ground radar, azimuth, and elevation. Then, according to the drift of the sounding balloon with the wind, the wind direction and wind speed can be calculated.

At the same time, the sonde will continuously send the collected temperature, humidity and air pressure data at different altitudes back to the ground, which will be received by the ground data receiving radar. The received signals will be decoded and transmitted to the computer terminal for display and drawing, thus completing the detection of high-altitude temperature, humidity, air pressure, wind direction and wind speed.

Weather balloon

Can it be released anytime and anywhere?

In fact, the release of meteorological sounding balloons requires an application for airspace and cannot be released anywhere. Generally, they can only be seen in places with high-altitude meteorological stations. The number of high-altitude meteorological stations is not as large as that of ground meteorological stations. There are tens of thousands of ground meteorological stations across the country, but only 120 high-altitude meteorological stations. Beijing has only one high-altitude meteorological station, located at the Nanjiao Observatory.

Similarly, the time of balloon release is not random, but fixed. If there is a high-altitude weather station in your city, then there will always be a time to encounter a high-altitude balloon at 01:15, 07:15, 13:15, and 19:15 Beijing time. No matter how bad the weather is, these weather stations will be open as usual!

The role of weather balloons

Weather balloons are an important means of controlling the changing weather conditions in the sky. Like a CT scanner, they scan layer by layer from the ground to the sky, achieving observations from two-dimensional to three-dimensional, providing rich high-altitude meteorological data for weather forecasting and promoting the improvement of forecasting capabilities.

Meteorological sounding balloons have also appeared many times in scientific expeditions to the Antarctic and the Qinghai-Tibet Plateau, providing data support for comprehensive assessments of climate change in these regions. High-altitude detection has been attempted since the mid-18th century, with kite detection, manned balloon detection, tethered balloon detection, and today's radio sounding. High-altitude detection technology has continued to innovate and develop. In the future, this balloon will work with China's Beidou positioning sounding instrument to fly higher and higher with the blessings and dreams of the Chinese people.

END

Author: Du Chuanyao

Senior Engineer, Beijing Meteorological Observatory (Beijing Observatory)

Editor: Guru