Global atmospheric electrical circuit Global atmospheric electrical circuit The global atmospheric electrical circuit is the course of continuous movement of atmospheric electricity between the ionosphere and the Earth. Through solar radiation, thunderstorms, and the fair-weather condition, the atmosphere is subject to a continual and substantial electrical current. Principally, thunderstorms throughout the world carry "negative" charges to the earth, which is then discharged gradually through the air in fair weather. This atmospheric circuit is central to the study of atmospheric physics and meteorology. It is used in the prediction of thunderstorms, and was central to the understanding of electricity. In the past it has been
Through-the-earth mine communications arriving in less than a minute." Through-the-earth mine communications Through-the-Earth (TTE) signalling is a type of radio signalling used in underground mines and caves that uses low-frequency waves to penetrate dirt and rock, which are opaque to higher-frequency conventional radio signals. In mining, these lower-frequency signals can be relayed underground through various antennas, repeater or mesh configurations, but communication is restricted to line of sight to these antenna and repeaters systems. Through-the-Earth transmission can overcome these restrictions by using ultra-low frequency (300–3000 Hz) signals, which can travel through several hundred feet of rock strata. The antenna cable can be located