Weather warfare. Well, with this evidence it would be near impossible to deny. One doesn't patent a device or process unless you want to protect it's distribution or disclosure. Here are some more for your perusal, and none of them are pending..if you catch my drift:

3601312 - August 24, 1971 - Methods of Increasing The Likelihood oF Precipatation By The Artificial Introduction Of Sea Water Vapor Into The Atmosphere Winward Of An Air Lift Region
3608810 - September 28, 1971 - Methods of Treating Atmospheric Conditions
3608820 - September 20, 1971 - Treatment of Atmospheric Conditions by Intermittent Dispensing of Materials Therein
3613992 - October 19, 1971 - Weather Modification Method
3630950 - December 28, 1971 - Combustible Compositions For Generating Aerosols, Particularly Suitable For Cloud Modification And Weather Control And Aerosolization Process
USRE29142 - This patent is a reissue of patent US3630950 - Combustible compositions for generating aerosols, particularly suitable for cloud modification and weather control and aerosolization process
3659785 - December 8, 1971 - Weather Modification Utilizing Microencapsulated Material
3666176 - March 3, 1972 - Solar Temperature Inversion Device
3677840 - July 18, 1972 - Pyrotechnics Comprising Oxide of Silver For Weather Modification Use
3722183 - March 27, 1973 - Device For Clearing Impurities From The Atmosphere
3769107 - October 30, 1973 - Pyrotechnic Composition For Generating Lead Based Smoke
3784099 - January 8, 1974 - Air Pollution Control Method
3785557 - January 15, 1974 - Cloud Seeding System
3795626 - March 5, 1974 - Weather Modification Process
3808595 - April 30, 1974 - Chaff Dispensing System
3813875 - June 4, 1974 - Rocket Having Barium Release System to Create Ion Clouds In The Upper Atmopsphere
3835059 - September 10, 1974 - Methods of Generating Ice Nuclei Smoke Particles For Weather Modification And Apparatus Therefore
3835293 - September 10, 1974 - Electrical Heating Aparatus For Generating Super Heated Vapors - Referenced in 3990987
3877642 - April 15, 1975 - Freezing Nucleant
3882393 - May 6, 1975 - Communications System Utilizing Modulation of The Characteristic Polarization of The Ionosphere
3896993 - July 29, 1975 - Process For Local Modification of Fog And Clouds For Triggering Their Precipitation And For Hindering The Development of Hail Producing Clouds
3899129 - August 12, 1975 - Apparatus for generating ice nuclei smoke particles for weather modification
3899144 - August 12, 1975 - Powder contrail generation