Weather Modification

The federal government has been interested to a greater or less extent in programs of hail and lighting suppression for more than two decades. Hail suppression is of interest because of the devastating effects that this form of precipitation can have on crops, while lighting suppression is of importance because of the many forest fires it causes.

The principle underlying most hail suppression research is that hail can be prevented if the atmosphere is flooded with nuclei on which moisture can condense and freeze. The more nuclei present, the argument goes, the less likely large pieces of ice (hail) are to form. Results of research on hail suppression thus far have not been especially encouraging.

Research on lighting suppression, while of considerable economic value, has so far not received a great deal of attention. One suggestion has been to seed thunderheads with very small aluminum fibers in an attempt to dissipate electrical charges in a cloud. Early research in the late 1960s and early 1970s produced some promising results, but relatively little work is now being done in the field.