Laserfiche WebLink
<br />CHAPTER I <br /> <br />.. <br /> <br />INTRODUCTION <br /> <br />Background <br /> <br />Artificial ice-phase seeding to modify the characteristics of rainfall and <br /> <br />hailfall from summertime convective storms has been in use by a variety of <br /> <br />governmental, academic, and commercial groups since shortly after Schafer (1946) <br /> <br />and Vonnegut (1947) discovered the ability of dry ice and silver iodide to stimu- <br /> <br />late glaciation in supercooled clouds. A wide variety of seeding projects elf all <br /> <br />levels of funding and sophistication have been conducted since that time with <br /> <br />decidedly mixed results. Rainfall decreases due to ice-phase seeding have been <br /> <br /> <br />documented by Braham (1966) in a carefully designed experiment, but rainfall in- <br /> <br />creases seem statistically significant in the Rapid Project in South Dakota C1nd in <br /> <br />the South Florida Cumulus Seeding Program. Negative rainfall effects due to <br /> <br />seeding have been found for the summer cumulus of the southern Arizona mountains. <br /> <br /> <br />Hail suppression due to seeding is claimed by Mather (1976) in South Africa and by <br /> <br /> <br />the Soviets in their hail suppressi?n program. <br /> <br /> <br />Yet, preliminary results from the U.S. National Hail Research Pro~,ram (NHRE), <br /> <br /> <br />while not statistically significant, seem to indicate the possibility of both hail and <br />