In Bulgaria, the method of delivery of reagent - artificial ice-forming nucleus (AgI) in clouds by rockets has been adopted. It enables the direct and continuous dispersion of reagent in seeding cloud areas.
The hail suppression concepts define: the seeding areas – the ones with high supercooled liquid water content and weаk updraft and the start of seeding – the early stage of development of hail dangerous clouds.
The strong updrafts provide new quantities of supercooled liquid water and carry up the ice crystals to its upper part (anvil). That is why, it is necessary to introduce ice-forming nuclei at regular intervals during the whole period of hail danger.
The effect of hail suppression activity reduces when the hail dangerous cloud comes to the protected area in a mature stage of development. The already formed hail falls to the ground. In these cases, cloud seeding reduces the further intensity of the process and the damages to agricultural crops.
The independent valuation of hail damages to the agricultural crops is made after every cloud seeding activity.
The overall hail suppression activity is carried out by the RAPIRA system. The system is designed to process and display the weather radar information from MRL5-IRIS, to process the aerological sounding data, to command and control the cloud seeding with seeding reagent and to command the anti-hail rockets launching.