`Change is not made without inconvenience," said Dr Samuel Johnson, and at no time is this more true than when it comes to experiments aimed at tampering with our weather.
Scientists are sceptical about the effectiveness of so-called weather modification. Every now and then, however, results are reported that are sufficiently encouraging to rekindle the enthusiasm of those who believe that some improvement can be brought about. "Cloud seeding" is a case in point.
The technique was popular during the 1950s and 60s, the idea being to impregnate a promising cloud by aircraft with tiny particles of suitable composition - usually silver iodide or dry ice (solid carbon dioxide). It was hoped these would act as a catalyst and induce the cloud to produce a heavy shower.
In simple terms, the idea was to convert a cumulus cloud into a cumulonimbus.
The technique, however, was unreliable. It could only be used where suitable large cumulus clouds already existed; the chemicals required were expensive; the induced shower might not fall where it was needed; and there was a "downside risk", in that successful attempts to enhance rainfall might be a good thing for the farmer who needs more rain, but what about his next-door neighbour whose crops need less, not more, precipitation?
Finally, there was considerable doubt as to whether the technique really worked at all or not: it was difficult to prove that any rain that fell was really "extra" rain - and not rain which might have fallen anyway.
Then there were those who were enthusiastic about seeding as a means of alleviating the damage done by hurricanes.
In such a storm, the "eye" around which the spinning winds rotate may be as little as 15 miles across; the idea behind the seeding was to expand the eye to, say, 30 miles or so in diameter, so the air would then revolve more slowly round the centre. This could be achieved, it was felt, by seeding the clouds in the area immediately outside the eye; as the seeded clouds developed disproportionately, a new and larger eye would be established.
The technique was first applied to a Caribbean hurricane in 1947, but there were red faces among those responsible when the seeded hurricane suddenly changed course and caused extensive damage over the US state of Georgia. Further experiments were tried in the 1960s, but some of the seeded hurricanes seemed to become even fiercer, some weakened in the way that had been hoped, others changed direction without any difference in intensity, and the rest just ignored the seeding altogether.