Rain-Making By Seeding Clouds Still Experimental

Press, Volume XCV, Issue 28179, 18 January 1957, Page 10

Rain-Making By Seeding Clouds Still Experimental

(Aew Zealand Press Association f

DUNEDIN, January’ 17. The majority of attempts at rain-making have not been susceptible to accurate physical assessment. said Dr. F. W. G. White, chief executive officer of the Australian Commonwealth Scientific and Industrial Organisation, in his presidential address to the physics section of the Science Congress today.

“These have given a *not proven’ answer.” he said. Many* previous attempts were, “in spite of the use of aeroplanes and modern physical equipment, no different in their scientific significance from the mystical activities of aboriginal medicine men.

“Although the experimental evidence, sufficiently satisfying to physicists, is as yet limited and the picture is confused by a large number of unsatisfactory approaches, nevertheless there is sufficient information to indicate that success in weather modification can be assured in certain clearly defined conditions,'* he added.

“The single cloud experiments give an unequivocal answer that clouds containing super-cooled water droplets extending over the freezing level to temperatures of minus five degrees centigrade or less, can be artificially stimulated to rain by the use of dry ice or silver iodide.’’ he said. Present experiments in the Snowy Mountains in Australia were giving promising results, but they would have to be continued for a more lengthy period before they would achieve statistical significance, he said. By these experiments it was hoped to produce ian economically significant inI crease in rainfall over a mountainous catchment area.