The Rainmaker 
Thursday, 5th March 1998 at 9.30pm on BBC2

Dr Graeme Mather has dedicated his entire working life to proving once and for all that clouds can be made to rain by human intervention. Now, after 30 years of fruitless searching, Graeme believes that he has made the breakthrough that will make cloud-seeding a legitimate science. Horizon tells the story of one man's persistence and his amazing discovery that could end droughts and revolutionise water management the world over. 
On graduating from university, Canadian-born Dr Mather was warned by his tutor: "Whatever you do, don't be seduced by the challenge of weather modification. You'll waste your time and your reputation." Graeme ignored that advice and embarked on a career that has seen numerous false dawns and attracted the growing scepticism of his fellow scientists. 
Then, just as Mather was on the point of accepting defeat, he had his eureka  moment, a chance observation that revealed a new way of seeding clouds. Suddenly the frustrations of 30 years were swept aside as he and his colleagues in South Africa put the new theory to the test. Seven years on, Graeme's discovery is now undergoing the final, independent trials that will prove its legitimacy. 
Cloud-seeding is not a new idea, but for over 100 years it has been more of an act of faith than a science, as meteorologists and drought-stricken farmers have tried seeding clouds with a variety of "magic ingredients", none of which worked to any measurable degree. The theory was fine, the practice was a failure. That is, until Graeme had his eureka moment. 
Graeme's breakthrough occurred when he observed that pollutants from a local paper-mill had an extraordinary effect on storms passing overhead - they rained harder and longer. Since then, he and his research company CloudQuest have worked tirelessly to perfect the technology that can repeat this phenomenon and to establish the data gathering techniques that prove it works. Their South African experiments have been impressive, recording increases in the rainfall from clouds of between 40-60%. 
Horizon goes to Mexico to witness the trials that finally seem to be vindicating Graeme's work, much to the astonishment of sceptics. Dramatic sequences of mid-air cloud-seeding and sudden downpours bear witness to a technological  revolution in the making. They also reveal the natural science that lies behind the visually spectacular, but secret world of clouds. 
For Graeme it marks the successful culmination of a life's work. Adam Bullmore and Denman Rooke's film tells the remarkable story of the triumph of persistence and good luck over failure and frustration. In his own words: "It's how science ought to work, but almost never does." But sadly, Graeme will never see the fruits of his work. Shortly before filming was completed, Graeme Mather died. 
External Links - The homepage of Graeme Mather's company in South Africa, with details of the experiment, background to the research and history of cloudseeding. - The National Centre for Atmospheric Research. - Has a number of links to the various instrumentation systems which are being used in the experiments seen in the film. - The European Thunderstorm and Hail Prevention Research Center. 

The BBC is not responsible for the content of external internet sites.