(note: edited from translated version for readability)
Artificial rain & cloud growth: a new Brazilian process
T. Imai, I. Martin, K. Iha
Instituto Tecnológico de Aeronáutica
São José dos Campos, Brazil
This project shows the development of a new process to provoke artificial localized rains with remarkable intensity, by seeding size controlled water droplets from aircrafts on clouds previously selected by meteorological radar.
This radar needs to be modified and calibrated for this special operation. The seeded droplet is similar to that [of] ones nature use[s] to produce rains.
The radar helps in the process by tracking clouds that are in conditions to cause rains over the desired area, for example, a hydrographic basin from a group of rivers or lakes to supply a city or a hydroelectric power plant; a reforested area or even an agricultural area.
The radar helps in determining the cloud’s position height, volume, trajectory, speed and water content. These parameters are important for the seeder airplane to find the cloud above the area where the artificial rain is necessary.
In the past the experiments that did not work out in warm clouds, they were based on seeding Silver Iodide vapors that act as agglutinants or Sodium Chloride that acts as humectants, while in our process we act[ivate] seeding [with] just pure drinking water, in [the] form of collector droplets of controlled size.
Sabesp, the biggest Brazilian Water Supply Company, localized in Sao Paulo city, verified in 2003 that we have produced 31% of [the] rain precipitation, in a period of 4.5 months, during the worst drought period season in the last 70 years (accordingly to its Hydrology Department).
In the rain and cloud growth operations they were verified, with close and similar clouds, according to radar information, and only in the seeded clouds growth and precipitation occurred.
We have completed 236 flight missions and we produced, artificially, 188 rains. In some cases, it was possible to produce 3 to 6 rains in different convective clouds in one flight only.