How can aircraft be used to disperse cloud-seeding materials?

Aircraft are used to disperse cloud-seeding materials through several specific methods, depending on the substance being deployed:

• Dry Ice: Crushed pellets of dry ice, typically ranging from less than a millimetre to a few millimetres in diameter, are dispersed directly from an aircraft as it flies over a cloud.1
• Silver Iodide: This substance is commonly introduced into clouds using generators suspended from the wings of an airplane, which burn a solution of silver iodide and sodium iodide in acetone to create ice nuclei. Alternatively, pyrotechnical devices—solid mixtures of silver iodide and an inflammable substance—can be dropped from aircraft into clouds, where they ignite to release the seeding material.12
• Water Sprays: To modify warm clouds, aircraft have been used to dispense water sprays or salt particles, such as sodium chloride, to encourage the growth of giant cloud droplets.1

While aircraft provide a direct means of delivery, it is important to note that some substances, such as salt-water sprays, can be corrosive to aircraft surfaces and require careful handling. Other methods of delivery, such as ground-based generators, rockets, and artillery, are also utilized in various weather modification programs.132