Measurement of Maxwell’s current density from a tropical station during severe lightning disturbances and fair-weather days of 2019

Abstract

A study of the global electric circuit can help us to understand the electrical environment of the Earth’s atmosphere. This approach provides a good frame work for exploring interconnections and coupling of various regions of the Earth’s upper atmosphere. With the aim of understanding the behaviour of air- Earth current system during severe meteorological disturbances, we carried out observations of Maxwell’s current (air-earth current) for a short period during lightning hours and fair weather days of 2019 at an equatorial station Tirunelveli (8.7° N, 77.8° E), located in southern part of India. Unusual lighting activity was noted during the peak summer of 2019 over this location and corresponding electric variability in air-earth current amplitude and phase charge in electric field were measured. During fair weather days, the current density is only a few pico amps; however, a tenfold increase in the current density was noted during disturbed weather conditions. Our analysis indicates that a rise in temperature led to enhanced convection during mid-day hours, which in turn, contributed to source activity. Possibly, this is the first report that brings out that the rise in temperature is covariant to source activity. We found the wind flow to be moderately southwesterly during the period of observation.