The practice of releasing radar chaff, which is aluminum or aluminum coated plastic strips or needles, into the atmosphere for the purpose of obtaining a strong radar reflecting signal in an otherwise weakly reflecting environment. Chaff seeding, as a research technique, has been used to study the motion, deformation, transport, and mixing processes of the atmosphere on scales from a few meters to a few kilometers. Chaff seeding has also been used on the hypothesis that corona discharge from the needle tips could reduce lightning from thunderstorms. See window.