Seeding single clouds using pyrotechnic cartridges, 1973-74


  • D. McNaughton


Weather Modification Research


Experiments conducted in 1968-69, which involved seeding single cumulus clouds using silver iodide burners mounted on an Air Force Dakota, indicated that the rainfall could be increased  by seeding suitable cells at about 14,000 ft a.s. l., just below  their centres. However, in an operation in which a large number  of clouds are dosed, it is much easier if the seeding can be  carried out from near cloud-top. This is because, firstly, the  turbulence inside a growing cloud is much less near the top than it is lower down. Secondly, it is important to seed only those  clouds which have attained sufficient height for the treatment to  work, the height being best estimated by flying at cloud-top  level. The top-seeding technique is different from that used lower down in the cloud, and separate confirmation of its  effectiveness is therefore necessary; this was the prime  objective of the 1973-74 experiments.....




Technical Notes and Correspondence