Background of "the Royal Rainmaking Project"
".. At that time, I looked up at the sky and saw that there were many clouds, but were all blown past the arid land. The solution lies on how to make those clouds fall as rain in the locality..." His Majesty King Bhumibol Adulyadej's initiative project "Royal Rainmaking" was derived during his visit of the 2nd to the 20th of November 1955 to fifteen dry and rough northeastern provinces.
On Monday, November 14th, 1955, while travelling by a green Dehaley Sedan car from Nakhon Phanom to Kalasin Province, passing Sakon Nakhon Province and the Phuphan mountain range, H.M. King Bhumibol Adulyadej noticed distress and hardship of his subjects and farmers who lacked water for consumption and agriculture. When he returned to Bangkok, he expressed his thoughts to M.R. Dehhbrihi Devakul, a renowned agricultural engineer.
Since 1955, after his initiative in weather modification for making rain, H.M. King Bhumibol Adulyadej spent fourteen years in researching, analyzing, and evaluating documents regarding meteorology and weather modification that were accepted by both domestically and by foreign countries until he was skilled and had confidence in realizing his ideas.Then, he expressed his ideas to M.R. Debbhri Devakul, an agriculture engineer who was an expert in research and invention at Ministry of Agricultural and Cooperatives. H.M. King Bhumibol Adulyadej also provided research papers and other information to M.R. Debbhri Devakul for supplementary study. One year later, H.M. King Bhumibol Adulyadej endorsed to finding a way to enable the flight seeding experiment.
The Theoretical Background
The first principle is to seed substances (sea salt) into the atmosphere by aircraft to absorb moisture, then use cold formula substances (dry ice) to make moisture condense and coalesce. (The initiative in weather modification for making rain)
The First Attempt at Royal Rainmaking
In 1969, the Ministry of Agriculture and Cooperatives established the Insecticide Aviation Unit, under the Rice Department. It was ready to support and respond to H.M. King Bhumibol Adulyadej’s desire. M.R. Debbhri Devakul informed H.M. King Bhumibol Adulyadej of the eager preparedness to launch the experimental operation. Accordingly, H.M. King Bhumibol Adulyadej directed to conduct during the year of the first actual flight experiment on the first and second of July 1969.
The Ministry of Agriculture and Cooperatives appointed M.R. Debbrihi Devakul for the director of the project and head of the experimental group. M.R. Debbrihi Devakul chose Khao Yai National Park to be a suitable test site. He started the first trial flight by seeding substances (dry ice, or solid carbon dioxide) of which the size was not greater than one cubic inch at the top of clouds. The height of this cloud which soared dispersedly over the test site was not over than 10,000 ft. Then, the cloud physical shape obviously changed. The cloud mass coalesced and condensed. Its top was built up higher and it became a large rain cloud rapidly and moved following with the wind direction. Unfortunately, rain could not be observed due to mountain peaks obscuring the view. However, according to the follow-up by field surveys and information received and confirmed by the populace, there was rain over the target area, Khao Yai National Park. This event demonstrated that control of clouds was possible.