The continuous operation terrestrial generators are an alternative to the rocket and aircraft impact technologies and are applied in the cases where the use or rockets and aircraft is complicated due to whatsoever reasons. The mode of action of the terrestrial generator is summarized as the formation of a considerable seeding area in the ground stratum which is later delivered into the cloud by the ascending flows. This results in the following restrictions with respect to the application of terrestrial generators:
- the time before the aerosol is introduced into the cloud is sufficiently long, therefore the generator must be powered on in advance, usually 2-4 hours prior to the commencement of the process of hail formation. Since the precise forecasting of the development of the process of hail formation for such time period is rather unreal, it is necessary to start the generators idly and respectively to have big consumption of reagent.
- for successful application of terrestrial generators is necessary to have knowledge of the specifics of the air flows in a given land area and an available model of the distribution of the aerosol introduced by the generators.
At the same time the application of terrestrial generators has its advantages which, if developed in detail, may outweigh the disadvantages:
- with an appropriate orography of the terrain (e.g. presence of mountain massifs and the necessary air flows) the impact with terrestrial generators may be more cost-effective than the rocket and aircraft impact methods. For example, there is information about Chinese experiments with generators with liquids (province of Tai’an, in the Taishan mountain, 1 500 m above sea level). The work of the generator ensures seeding of a considerable area of the plain and may be used both for antihail purposes and increase of the quantity of precipitations.
- when terrestrial generators are used, the compact scheme of the generator is no longer necessary; more complex sublimation processes become possible to organize which results in minimized consumption of silver or absolute withdrawal from the use of silver (generators of aerosols of copper acetylacetonate, phloroglucinol, etc).
We have started to work on the development of a terrestrial generator for ice-forming nuclei on the basis of copper acetylacetonate (not containing silver compounds). The mass production of copper acetylacetonate is cheap and environmental friendly. The generator itself is sufficiently prospective; however it must provide for a firm need of such generator on part of the Contracting Authority.
Presently Stroyproject offers a model of terrestrial pyrotechnical generator for ice-forming nuclei „Loza-250” (on the basis of silver compounds) with the following parameters:
Combustion time of the pyrotechnical element, min.
7
Weight of the pyrotechnical composition per element, grams
21
Total weight of the pyrotechnical composition, grams
714
Production of active nuclei of a pyrotechnical element at
-100C
4.2x1014
Total production of active nuclei at
-100C
1.43x1016
Pyrotechnical elements per stand
*
34
Total useful time of the generator, hours
*
4
Remote start
Provided for
*
may be changed in any direction upon customer’s request
Comparison of the production of a terrestrial generator and available analogues:
Production of nuclei per gram composition
Note
Pyrotechnical element of the generator „Loza-250”
-3.20C
1.61E+11
-6.00C
9.95E+12
-9.80C
3.09E+13
Test of RPA Typhoon, Russia, May 2008
GIP2000 Acetone generator, Sweden
-150C
1.00E+13
According to manufacturer's data
Acetone generator, Ice Crystal Eng., LLC, North Dakota
-100C
1.60E+12
According to manufacturer's data
Acetone generator, НАГ AgI -0,5 NaI ANELFA, France
-150C
0.80E+12
According to manufacturer's data
Acetone generator, НАГ AgI – KI Chile
No data
Therefore, we have reasons to assume that the use of terrestrial generator based on pyrotechnical elements is considerably more effective than acetone generators which are more common in a real impact situation.
