Solar- Terrestrial Physics, in its broadest sense, is concerned with the transport of energy, particles, and fields from the sun to the earth and their consequent effect on the terrestrial environment. Most of the solar energy eventually deposited in our atmosphere, at a rate of approximately a trillion megawatts, arrives in the form of visible light. The study of how this energy affects our environment falls within the purview of meteorology, a discipline that has experienced an independent development and that has sufficiently different problems from solar-terrestrial physics that it can be regarded as a separate but neighboring discipline. In contrast, solar-terrestrial physics is concerned with the higherenergy radiations (ultraviolet, x-ray, and gamma-ray) that carry a relatively small amount of power (approximately a million megawatts), but nevertheless have significant and highly variable effects on the terrestrial environmen
