New Attempts To Make Rain In West Pakistan

Press, Volume XC, Issue 27370, 8 June 1954, Page 6

New Attempts To Make Rain In West Pakistan

X PARIS. Experiments aimed at bringing more rain down over the parched soil of West Pakistan without using the expensive method of seeding clouds from a plane will be continued for the second successive year this July and August by a team of scientists from the Pakistan Government and the United Nations Educational, Scientific and Cultural Organisation.

Plans for the experiments were outlined recently by Dr Michael Fournier d’Albe of London, a British physicist who is now a member of a UNESCO geophysical mission working in Pakistan under the United Nations technical assistance programme. They will follow tests conducted last August and September in- Pakistan’s North-west Frontier Province near the Khyber Pass. In these experiments, Dr Fournier d’Albe Reported, observers were first posted with rain gauges for six weeks to 23 Pathan villages to measure normal rainfal? before any cloud-seeding attempts were made. Between August 25 and August 31, Royal Pakistan Air Force jeeps sprayed salt solution over roads radiating out of the city of Mardan. The purpose of this “ground seeding” was to increase the number of rainproducing salt particles in the atmosphere but no results were apparent at first

Rainmakers usually aim at precision —waiting for the right wind to bring the right cloud to the right place—and then dropping the right substance into the cloud. The Pakistan experiment differs, in that the effort is being made to modify the atmosphere sufficiently to produce rain when the right combination of conditions occur. Winds carry the salt particles thousands of feet into the air, where they remain in sufficient density, for a time, to cause drops to form in moisturebearing clouds, when they arrive. Evaluation of Tests Tests were also made with direct seeding of clouds from planes. Between September 1 and 5, five flights were made with, training planes. In this case a salt solution was sprayed directly into the clouds. Four of the flights were unsuccessful, but the results of the remaining one are still being studied. That day, a plane went up under a sky covered with cumulus clouds. It left a wake of rain showers falling behind it 30 to 40 minutes after it had sprayed each cloud. Dr. Fournier d’Albe, a cautious scientist, believes that the plane “might have accounted” for this rainfall. However, is much more interested in the results of the groundsalting carried out by jeep. Although no change in the atmosphere had been registered by his instruments which “count” salt particles present in the air, he later learned, when reports from scattered observers reached him, that the area around Mardan had a two-inch rainfall after this experiment. It is this method of increasing salt particles by dispersal from the ground which will be given another trial during this year’s monsoon season.

iCloud-seeding by air over an area as large as West Pakistan is not economically feasible. It is easy to understand why’ the Pakistan Government is anxious to do something about the weather. Jacobad, in West Pakistan and on the railway running north from Karachi to Lahore, is the hottest place on the sub-contin-ent, with temperatures up to 127 degrees during the summer. It receives only four inches of rain a year, and three of these come during the monsoon season. Karachi, on the sea, has only seven inches of rain a year and the Sind deserts behind it are among the world’s driest. The province of Baluchistan is dry and barren and the North-west Frontier Province is considered fortunate because it receives 15 inches of rain a year (compared to some regions of East Pakistan, on the other side of the sub-continent, where 200 inches fall annually). • - Extension of Monsoon Ideally, what West Pakistan would need is. a way of extending the southwest monsoon to the mouth of the Indus River. Then the Indus delta would be as fertile as that of the

Ganges, but extending monsoons is a day-dream that belongs in the pages of science fiction. What Pakistan’s meteorologists hope to do is to tap some of the clouds that blow over West Pakistan during the monsoon season.

formation of clouds themselves and the movements of weather systems are beyond human control,” Dr. Fournier d’Albe said. “The only way in which man can influence rain is by altering the nature of the small particles or ‘condensation nuclei’ upon which cloud droplets form.” There are two types of these particles: ice-forming nuclei which speed the freezing of cloud droplets to set off rain and “large” hygroscopic or water-collecting nuclei (about one hundredth of a millimetre in diameter) which form rain droplets by capturing tiny cloud droplets. In most attempts at increasing rainfall, experimenters try to accelerate the freezing of cloud tops by dropping dry ice into them. In West Pakistan, however, ice-forming nuclei do not have much of a hand in natural rainfall and this method is not suitable.

Experiments conducted by Pakistan’s meteorological department over the last three years show that hygroscopic nuclei are responsible for most of the scant rain that the country receives. In other words, increasing their number might increase rainfall. But studies also show that these nuclei—in the form of salt particles—are so abundant over certain areas, such as Karachi and the Sind desert, that there is no hope of inducing rainfall by putting more of them into the atmosphere. These regions are dry simply because of inadequate cloud formations. However, in the North-east Frontier Province and in Baluchistan, hygroscopic nuclei are not nearly as plentiful. It is here that the scientist has hopes of increasing rainfall by salting the air.