The damage caused by hail, worldwide, is very important. Thus, annual losses of approximately 5-6 billion American dollars (USD) are recorded.

For this reason, many countries have studied the phenomenon of hail, but also the ways to combat it. At the beginning of this century, anti-hail projects were applied in over 48 countries, protecting over 88 million hectares of agricultural crops.

Worldwide, to combat hail, several categories of means and/or methods of protection are used, such as means of active interventions in the atmosphere that use certain substances to seed convective clouds:

• the rocket method – applied in Russia (2.5 million ha), Bulgaria, Italy, Moldova, Uzbekistan, Serbia, Ukraine, Argentina, Macedonia, Tajikistan, Romania, China (over 40 million ha);

• the aviation method – it is used in the USA, Canada, Austria, Germany, Greece, Argentina; from 2019, local experiments also started in Romania;

• the terrestrial generators method – applied in France, Italy, Hungary, Brazil, Germany, Spain, Holland;
• the artillery method – applied through 18 projects in China, Mongolia

Passive means of protection against hail, which do not use active interventions in the atmosphere:

• the anti-hail method of nets, placed over the area to be protected, on relatively small surfaces
• the sonic generators (cannons), which are used in many countries in central and western Europe; their effectiveness is not recognized by the WMO (World Meteorological Organization), because it could not be scientifically proven;
• the combined method: involves the simultaneous use of two or more methods presented above.

These methods have been studied in depth, in certain countries that, over the years, have introduced and perfected certain technologies, turning into real schools in the field, as follows:

• the Russian school – for the rocket method
• the American school – for the aviation method
• the French school – for the terrestrial generators method