Extensive layer clouds in the global electric circuit: their effects on vertical charge distribution and storage

Abstract

A fair-weather electric field has been observed near the Earth's surface for over two centuries. The field is sustained by charge generation in distant disturbed weather regions, through current flow in the global electric circuit. Conventionally, the fair-weather part of the global circuit has disregarded clouds, but extensive layer clouds, important to climate, are widespread globally. Such clouds are not electrically inert, becoming charged at their upper and lower horizontal boundaries from vertical current flow, in a new electrical regime—neither fair nor disturbed weather; hence it is described here as semi-fair weather . Calculations and measurements show the upper cloud boundary charge is usually positive, the cloud interior positive and the lower cloud boundary negative, with the upper charge density larger, but of the same magnitude (∼nC m −2 ) as cloud base. Globally, the total positive charge stored by layer clouds is approximately 10 5 C, which, combined with the positive charge in the atmospheric column above the cloud up to the ionosphere, balances the total negative surface charge of the fair-weather regions. Extensive layer clouds are, therefore, an intrinsic aspect of the global circuit, and the resulting natural charging of their cloud droplets is a fundamental atmospheric feature.

Modeling of Spherical Dust Particle Charging due to Ion Attachment

“…In this region as the conductivity increases to the initial fair weather values, the electric field decreases. Similar behavior has been derived by Zhou and Tinsley (2007), and by Harrison et al (2020) in layer clouds. This has to do with the reduction of the current density due to the increase of the columnar resistance caused by the conductivity reduction inside the layer (Rycroft et al, 2008).…”

“…While the dust particles are aloft, and in the absence of any charge separation within, the electric field at the ground decreases as a consequence of the increase of the columnar resistance as has been shown by Harrison et al (2020) and Daskalopoulou et al (2021). As dust particles approach the ground and the electrical conductivity decreases, because the dust particle number density increases, the electric field increases.…”

Responses of the AC/DC Global Electric Circuit to Volcanic Electrical Activity in the Hunga Tonga‐Hunga Ha'apai Eruption on 15 January 2022

“…Harrison et al. (2020) quoted 4 × 10 −14 S/m, while the hybrid model of Kudintseva et al. (2016, Figure 5) yields about 1.25 × 10 −14 S/m.…”

“…Due to its high variability, the latter is challenging to estimate. Harrison et al (2020) quoted 4 × 10 −14 S/m, while the hybrid model of Kudintseva et al (2016, Figure 5) yields about 1.25 × 10 −14 S/m. The corresponding relaxation times are 3.7 and 11.8 min, respectively.…”

An Alternative Methodology of Fair‐Weather Identification for Ground‐Based Measurement of AEF at the Polar Region

“…Nicoll and Harrison (2016) measured the electric charge density inside the stratus clouds by using a charge sensor on a balloon. Using the data of the electric charge density measured by Nicoll and Harrison (2016), Harrison et al (2020) showed that the magnitude of the positive charge at the upper and that of the negative charge at the lower boundary of extensively broad stratus clouds was equal. This implies that when there are charges of the same magnitude and different polarities at the upper and lower edges of the cloud, the electric fields above and below the cloud are not observed ideally.…”