| Popis: |
We give a brief overview of our present understanding of the global circuit formed by the atmosphere, the ionosphere and the solid and ocean surface of the Earth. The circuit is driven by currents (∼1 kA) above both thunderstorms and electrified shower clouds up to the ionosphere, which is presumed to be an equipotential surface (∼250 kV with respect to the Earth). This large scale circuit is completed by currents (∼2 pA/m2) flowing down through the fair weather atmosphere to the Earth’s surface and up into the atmosphere below the electrically active clouds. Using a realistic profile of the atmospheric electric conductivity, we have generated a model of this equivalent circuit using the PSpice electrical engineering software package. The effects of model lightning discharges on the circuit have been estimated numerically. Model sprites exhibiting mesospheric discharge processes have been constructed, first for negative cloud‐to‐ground discharges (−CGs), then for discharges transferring positive charge to... |
