Rain for Australia

Scientific rainmaking has suffered in the U.S., where it was first tried, from too much free enterprise. The rain-thirsty parts of the country are teeming with commercial rainmakers, most of them only faintly scientific. Their rosy promises, seldom justified, have discredited all "experimental meteorology" with a large part of the public.

In Australia, rainmaking has enjoyed a better-regulated infancy. According to Welsh-born Dr. George Edward Bowen, a leader in the development of both radar and radio astronomy, Australia's carefully controlled program of "cloud physics" experiments has yielded clear and encouraging results.

Most of the Australian experiments backed by CSIRO (the Commonwealth Scientific and Industrial Research Organization) have been done with Dry Ice sown from airplanes. Single clouds were seeded and the results watched by radar, which shows the formation of rain inside the cloud. A cloud-seeding was counted as successful only if rain came from the seeded cloud but not from adjacent clouds that were not seeded. When a cloud's temperature was below 19DEG F., the trick worked every time. Individual clouds dropped as much as 1/2 in. of rain that would not have fallen naturally.

Dr. Bowen does not advise silver-iodide seeding from ground generators. He has tried it with little success except on clouds that would probably have yielded rain anyway. On the other hand, he got good results by spraying water into warm clouds containing vertical currents. Such clouds produce much of Australia's rain.

Plenty of seedable clouds, says Dr. Bowen, drift over Australia without springing a leak. An area of some 1,000,000 sq. mi. to the west of the Great Dividing Range of eastern Australia is chronically in need of rain, and Bowen is sure that cloud-seeding can increase the precipitation of this area by a critical 50%. In northern Australia, the important thing is to make the rain come at the right time. This can be done, Bowen thinks, by seeding the yearly monsoon clouds, which often build up for weeks before rain begins to fall.

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