An Appraisal of Cloud Seeding as a Means 

 of Increasing Precipitation^ 



By Henry G. Houghton 



Massachusetts Institute of Technology 



The tremendous economic implications of the artificial control of 

 rainfall have led to overoptimistic statements in the public press and 

 to ill-advised commercial applications of rain-making techniques by 

 persons who do not possess the necessary technical qualifications. 

 These events have been viewed with concern by all responsible mete- 

 orologists. It is unfortunate that much of the money which has been 

 spent by public and private agencies in an effort to increase precip- 

 itation in specific areas has contributed so little to our scientific under- 

 standing of the processes involved. Without adequate scientific 

 information it is impossible to determine, with any assurance, the 

 economic value of cloud seeding or to prescribe the most favorable 

 conditions and procedures. 



As in the case of all scientific research, the several groups and 

 individuals who are working in this field have criticized one another's 

 experiments and interpretations. This normal scientific interchange 

 has been unduly accentuated by the glare of publicity which has caused 

 some of those concerned to be more dogmatic than is justifiable in 

 view of the present incomplete information. In the view of the public 

 the meteorological world has been divided into believers and non- 

 believers. This is an unfortunate and ridiculous concept. The fact 

 is simply that the information at hand is not sufficient to permit an 

 unequivocal conclusion regarding the possibilities of the artificial 

 control of precipitation. 



It is the purpose of this paper to assess the seeding techniques for 

 stimulating precipitation on the basis of present scientific information 

 and to point out the more significant gaps in our knowledge. The 

 writer has not been associated with any of the research groups in this 

 field but has kept himself informed through the literature and per- 

 sonal contact with many of the active investigators. For the sake of 



» Reprinted by permission from the Bulletin of the American Meteorological Society, 

 vol. 32, No. 2, February 1951, 



175 



