1. Research and development and experiments by state and federal agencies, institutions of higher learning and bona fide nonprofit research organizations.
2. Laboratory research and experiments.
3. Activities required in emergencies for protection against fire, frost, sleet or fog.
4. Activities normally engaged in for purposes other than those of inducing, increasing, decreasing or preventing precipitation or hail.
(Added to NRS by 1961, 693; A 1967, 159)