Fig. 4.

(a) The diurnal variations of the scattered and the averaged values (red color) of the observed Maxwell current density, the potential gradient, and the air-Earth current density at Maitri for group one and group two days. (b) The same as Fig. 4(a) but for the small ion (mobility >0.77 cm² V⁻¹ s⁻¹; diameter <1.45 nm); intermediate ion (mobility 1.21 × 10⁻²−0.77 cm² V⁻¹ s⁻¹; diameter 1.45–12.68 nm) and large ion (mobility 0.97 × 10⁻⁴–1.21 × 10⁻² cm² V⁻¹ s⁻¹; diameter 12.68–130 nm).