Fair weather space charge distribution in the lowest 2 m of the atmosphere

Abstract

Atmospheric space charge at 0.1, 1, and 2 m above the ground and the potential gradient have been measured in fair weather on level ground. Very large negative space charge values of up to 2 orders of magnitude larger than the normal daytime positive values have been observed to prevail during nighttime when the winds are calm. Changes in the polarity of space charges from positive to negative in the evenings, and from negative to positive in the mornings, are rapid and seem to coincide with the change in sign of the lapse rate at these levels. Nighttime negative space charge density decreases with height, and the daytime positive space charge density increases with height. Enhancement of potential gradient just after sunrise coincides with the morning reversal of the space charge polarity throughout the 2‐m height. The results support the view that convection currents comparable to conduction currents may flow at these levels. Short time changes in space charge density have been studied to show the inhomogeneity in space charge distribution close to the ground. Manifestation of the electrode effect has been observed. Different space charge distributions observed at different times of the day have been discussed with reference to the prevailing meteorological conditions.