Geoengineering involves injecting substances into the atmosphere to alter weather patterns. Blue-colored rain is caused by chemicals: - copper sulfate - and or aluminum oxides ....... which are sometimes used in cloud seeding experiments. These substances can give rain a blue tint. Copper sulfate and aluminum oxides cause blue-colored rain. Copper sulfate's copper ions bind to water molecules, scattering light and giving a blue hue. Aluminum oxides create a similar effect. Th