Abstract
The hypothesis used for the initial Climax wintertime cloud seeding experiment and for subsequent Climax replication-type experiments are described and briefly discussed. More recent physical studies of Colorado orographic clouds and seeding hypotheses are briefly summarized. These later tests and studies of orographic cloud seeding hypotheses emphasized direct and remotely sensed cloud and precipitation measurements utilizing instrumentation and modeling capabilities not available during the Climax statistical experiments. The conclusions suggested from the hypothesis testing, considering both the statistical experiments and the later physical studies, are summarized.
