We begin by reviewing the modus operandi of the global atmospheric electric circuit, for which the sources (drivers) are thunderstorms and electrified rain clouds; these provide upward directed influences on the circuit. With the ionosphere being an equipotential at ~ +250 kV with respect to the good conducting Earth (land and oceans), the load in the circuit is the electrical resistance of the fair weather atmosphere. The circuit exhibits variability with both space and time, ranging over ~ fifteen orders of magnitude or more. The main solar-terrestrial, downward directed influence on the global circuit is due to the spatially and temporally varying flux of galactic cosmic rays and to energetic electrons precipitating from the magnetosphere. A first order electrical engineering model (with the only spatial variable being height, and without temporal variations) has been constructed using the PSpice software package, and some interesting results obtained when using this are described. Next, some new experimental observations on the variation of the ionospheric potential over the solar cycle, on variations of atmospheric electricity parameters with a periodicity of 1.68 years, on electrical charges associated with the edges of low level clouds, and on precursor effects in the ionosphere linked to enhanced radon emissions from the ground before major earthquakes are presented. The paper concludes with some thoughts regarding future research in the subject.