Exploring the air
In order to have a three-dimensional view of the atmosphere it is necessary to record observations at the higher altitudes, and not only at ground level. For this, special instruments are used to enable meteorological data collection at different altitudes.
A meteorological probe consists of a radioprobe, which records the principal atmospheric parameters (temperature, pressure, humidity), that is attached to a rubber balloon which has been partially filled with hydrogen and helium. The balloon is freed and as a result of the expanding gas, it rises at a relatively constant speed, recording the data at the different altitudes. Around 20-30 km, the balloon explodes and the radioprobe, containing the recorded data, falls back to the ground attached to a small parachute. The data are transmitted via radio to the processing unit. By interpreting the recording, it is possible to have a reconstruction of the meteorological parameters of a vertical section of the atmosphere up to an altitude of 20,000 m. Together with the vertical movement of the balloon it is also possible to evaluate the direction and speed of the winds at the different altitudes. Meteorological probes are freed from the weather stations several times a day, at the times that are preset by the World Meteorological Organization (at 00:00-06:00-12:00-18:00 hrs).
Use of rockets that are launched specifically for meteorological observations is quite limited, and about twenty weather stations worldwide use them. In fact these are costly systems that cannot be used in densely populated areas. However they offer the possibility of direct and detailed recordings of numerous atmospheric data. When the rocket reaches the highest point of its trajectory, it frees a radioprobe that is analogous to the one used for the meteorological probes, which slowly descends with its parachute recording the principal meteorological parameters that are subsequently transmitted to the station on ground by radio.