GLOBAL ELECTRIC CIRCUIT INFLUENCES ON CLOUD MICROPHYSICS AND PRECIPITATION WITH CONSEQUENCES FOR ATMOSPHERIC CIRCULATION

B. A. Tinsley
University of Texas at Dallas

 

Abstract:

  The current flow in the global electric circuit links space weather and changes in the upper atmosphere levels down to tropospheric cloud levels, where it appears to influence precipitation from certain types of clouds, that in turn may influence atmospheric dynamics, providing a link between solar activity and weather and climate. The current flow depends also on the number of tropical thunderstorms active at any one time, that act as electrical generators for the circuit, so there may be an influence on global cloud cover of the strength of tropical convection. A brief review will be given of the effects on the global circuit of energetic particle precipitation and changes in polar cap ionospheric potential. The energetic particles are galactic cosmic rays (at all times) and MeV electrons and solar protons (occasionally, provided the stratospheric column resistance is enhanced by volcanic aerosols or stratospheric clouds).

  The current density into clouds generates space charge in conductivity gradients, such as at the upper and lower boundaries of the clouds, and provides the charge needed for two cloud microphysical processes; electroscavenging and ion-mediated-nucleation. Both processes appear capable of affecting the concentrations of CCN in certain types of clouds, such as marine stratocumulus. Electroscavenging also enhances contact ice nucleation in cloud tops that are supercooled with broad droplet size distributions. All of these processes can enhance precipitation and reduce cloud cover. Enhanced precipitation in certain circumstances can lead to intensification of winter cyclones, with possible consequences for blocking situations in the general circulation.

 

 


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