Recent advances in high energy atmospheric physics

Lightning and laboratory sparks were long assumed to involve only low-energy electrons and so were considered to be entirely conventional discharges. With the discovery of energetic radiation from natural and rocket-triggered lightning and from long laboratory sparks, we now know that these discharges often produce runaway electrons that may be accelerated to hundreds of keV in energy. Furthermore, thunderstorms have been observed to produce MeV gamma-ray glows, lasting seconds to minutes, and short (<; 1 msec) but intense terrestrial gamma-ray flashes (TGFs). The TGFs also launch terrestrial electron beams (TEBs) into space where they may be observed thousands of km away. These observations show that both thunderstorms and lightning are generating very high electric fields capable of producing large numbers of energetic electrons. These energetic electrons may produce currents that influence the system, and so it is important to understand their properties. In this paper, an overview will be given of the new field of High Energy Atmospheric Physics, which includes the x-ray and gamma-ray observations of thunderstorms and lightning, along with the physics of relativistic runaway electrons.