Researchers using a retrofitted spy plane discovered that tropical thunderstorms emit long-duration gamma-ray glows and a newly identified phenomenon called flickering gamma-ray flashes (FGFs). Published in Nature, the studies reveal FGFs as weaker but distinct from known Terrestrial Gamma-ray Flashes (TGFs) and glows, acting as a “missing link” between the two. FGFs are radio silent but often followed by radio pulses linked to lightning initiation. The NASA-owned ER-2 plane detected gamma-ray glows over vast areas, uncovering over 100 weak TGFs previously undetectable from the ground.