“ seeds ” into supercooled clouds which can remain a liquid even at temperatures as low as -40 degrees ( negative 40 degrees is the same temperature for both fahrenheit and celsius ). ( S3 ) They now mostly use silver iodine to cloud seed instead of dry ice because it works better . ( S4 ) It is true that silver iodide is considered a toxin by the Environmental Protection Agency , but the amount used for cloud seeding is not enough to be considered dangerous ( S1 ). The method to cloud seed with silver iodine is the same as the method for dry ice . But in my survey most people prefered dry ice because its cleaner ( PS )
In addition , there are now newer experimental methods such as dynamic cloud seeding which evaporates water into clouds , and there is also hygroscopic cloud seeding which dispenses salt into clouds , then