Progress on the realization of innovative low cost disposable hail sensing probes

Detailed studies and researches about hail characterization are considered to play a key role both in weather prediction and potentially also in damage assessment after a strong hail event occurred. Most monitoring instruments perform indirect monitoring operations, sensing the parameters from a remote position and not being directly inside a hailstorm. Since 2015 the CINFAI (Italian National Consortium for the Physic of Atmospheres and Hydrospheres) with its local operative research unit at the DET (Department of Electronic and Telecommunications) of Politecnico di Torino, Italy, realized a first preliminary study concerning the realization of artificial disposable sensing probes to study and monitor hail (conducted within a project called HaSP, founded by Regione Piemonte, Italy) [1]. The study was continued in cooperation with EST (Envisens Technologies s.r.l.), a small Italian engineering company, in order to realize the first small prototypes. Introducing the appropriate modifications, a similar version of the probes can be also suitable for monitoring atmospheric parameters [2]. Aim of this work is to present the progress on the realization of low cost disposable hail sensing probes for remote sensing and the study of the properties of hail. The probes are designed as artificial hailstones in order to study both the physical properties of the portion of atmosphere where the formation of hail occurs and the modification of atmospheric conditions while the hailstones are falling to the ground. For this reason, the probes and the hailstones should have the most similar as possible fluid-dynamic properties. The artificial probes can be dropped by a plane, or potentially by a UAV (Unmanned Aircraft Vehicle) if permitted by specific legislation, which fly above and through the clouds where the hail formation occurs. Each probe is equipped with different sensors and during their falling to the ground, they directly measure different physical parameters (e.g humidity, temperature, pressure, acceleration…). All data are sent to a receiver located on the ground exploiting a specific communication link realized at a frequency not affected by the presence of hail and water in the atmosphere. The hail sensing probes can be used for efficient monitoring operations and studies of hail formation dynamics and conditions, thus increasing the set of instruments used for monitoring, remotely sensing and study the physical properties of hail, and possibly also to improve the hail forecasting models.